Rfid tag sensors and methods

ABSTRACT

Radio frequency identification (RFID) devices for use in RFID-based sensors and related methods are described herein. In one implementation, an RFID sensor system includes an RFID device having a near field only RFID tag and a conductive element which functions as a far field antenna. A coupling structure selectively locates the near field only RFID tag and the conductive element in at least a first position and a second position relative to each other; wherein in the first position, the RFID device only operates in a near field, and in the second position, the RFID device operates in both the near field and a far field. The system may also include an RFID reader and controller located within the far field to read the RFID device only when the coupling structure locates the components in the second position.

This application is a continuation-in-part of U.S. application Ser. No.12/721,527, filed Mar. 10, 2010, entitled UNIVERSAL RFID TAGS ANDMANUFACTURING METHODS, which claims the benefit of U.S. ProvisionalApplication No. 61/159,042, filed Mar. 10, 2009, both of which areincorporated in their entirety herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to radio frequencyidentification (RFID) tags, and more specifically to RFID tags suitablefor use in near and far range applications.

2. Discussion of the Related Art

A radio frequency identification (RFID) tag is an object that can beapplied to or incorporated into a product, animal, or person for thepurpose of identification and tracking using radio waves. Some tags canbe read from several meters away and beyond the line of sight of thereader. Most RFID tags contain at least two parts. One is an integratedcircuit for storing and processing information, modulating anddemodulating a radio-frequency (RF) signal, and other specializedfunctions. The second is an antenna for receiving and backscattering thesignal. There are generally two types of RFID tags: active RFID tags,which contain a battery, and passive RFID tags, which have no battery.Today, RFID is used in enterprise supply chain management to improve theefficiency of inventory tracking and management.

Wal-Mart and the U.S. Department of Defense have published requirementsthat their vendors place RFID tags on all shipments to improve supplychain management. Typically, vendors use RFID printer/encoders to labelcases and pallets that require electronic product code (EPC) tags. Thesesmart labels are produced by embedding RFID inlays inside the labelmaterial, and then printing bar code and other visible information onthe surface of the label.

However, vendors face significant difficulties implementing RFIDsystems. For example, the successful read rates currently run only 80%,due to radio wave attenuation caused by the products and packaging. Thatis, the RF characteristics and performance of a RFID UHF passive tagvary depending on the dielectric properties of the object it is placedon. Tag inlay manufacturers attempt designing tags that are the leasteffected by the object's dielectric. The dielectric of the item the tagis attached to changes the resonate frequency of the inlay's antenna. Inorder for the RF signal to get to the integrated circuit there has to bean impedance matching between the antenna and the chip. The more theantenna is detuned, the greater the impedance is mismatched. The tag'sperformance degrades as the impedance mismatch increases until the tagstops working.

Inlay manufacturers have had only moderate success at designing“universal tags” that will reliably function for all uses. Thealternative is to design specific tags for specific types of product. Asa further challenge, vendors will need to design tags that will meet tagcertification which requires a particular tag be used for properperformance so that the tag can be read under many varying conditionsthrough out the supply chain. This will lead to even more productspecific tag designs.

Additionally, the manufacturers of consumer products will have to keepinventory of all the different tags that are required to sell theirproducts. The right tag for a particular stock keeping unit (SKU) willhave to be added to the Bill of Materials as a component and be managedthrough Materials Requirements. Planning (MRP). This adds one more linkthat can potentially stop the productions line for that SKU. There willbe great pressure to substitute a different non-certified tag in orderto keep the production line moving which will cause inventoryinaccuracies down the supply chain. The burden to the supply chain bothin cost and complexity creates a head wind that suppliers to retailersthat require RFID tagging have to overcome.

SUMMARY OF THE INVENTION

Several embodiments of the invention provide radio frequencyidentification (RFID) devices for use as RFID-based sensors, and relatedmethods.

In one embodiment, a radio frequency identification (RFID) sensor systemcomprises an RFID device comprising: a near field only RFID tag, whereinthe near field only RFID tag in and of itself does not function as a farfield RFID tag; a conductive element independent from the near fieldonly RFID tag and configured to function as a far field antenna; and acoupling structure coupled to the near field only RFID tag and theconductive element, wherein the coupling structure is configured toselectively locate the near field only RFID tag and the conductiveelement in at least a first position and a second position relative toeach other. The first position locates the near field only RFID tag andthe conductive element relative to each other such that the conductiveelement is sufficiently decoupled from the near field only RFID tag inorder that the RFID device only operates in a near field with respect toan RFID reader. And the second position locates the near field only RFIDtag and the conductive element relative to each other such that theconductive element is sufficiently coupled to the near field only RFIDtag such that the RFID device operates in both the near field and a farfield with respect to the RFID reader.

In another embodiment, a method for using a radio frequencyidentification (RFID) device as a sensor comprises: locating a nearfield only RFID tag and a conductive element of an RFID device at one ofa first position and a second position relative to each other, whereinthe near field only RFID tag in and of itself does not function as a farfield RFID tag, wherein the conductive element is configured to functionas a far field antenna, wherein the first position locates the nearfield only RFID tag and the conductive element relative to each othersuch that the conductive element is sufficiently decoupled from the nearfield only RFID tag in order that the RFID device only operates in anear field with respect to an RFID reader, wherein the second positionlocates the near field only RFID tag and the conductive element relativeto each other such that the conductive element is sufficiently coupledto the near field only RFID tag such that the RFID device operates inboth the near field and the far field with respect to the RFID reader;and locating the near field only RFID tag and the conductive element atanother of the first position and the second position relative to eachother.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features and advantages of severalembodiments of the present invention will be more apparent from thefollowing more particular description thereof, presented in conjunctionwith the following drawings.

FIG. 1 is a diagram illustrating the basic components of an RFID systemincluding a passive RFID tag and tag reader as is conventionally known.

FIG. 2A is a diagram of an RFID tag including an integrated circuit chipand an antenna formed on a substrate as is conventionally known.

FIG. 2B is a diagram of a near field only RFID tag including anintegrated circuit chip formed on a substrate according to oneembodiment.

FIG. 2C is a diagram of a near field only RFID tag including anintegrated circuit chip formed on a substrate to allow for capacitivecoupling with a far field antenna according to another embodiment.

FIG. 3A is a diagram of a decoupled near field only RFID tag and a farfield antenna located in proximity to provide a magnetic couplingtherebetween such that the near field only RFID tag and the far fieldantenna function in both the near field and the far field in accordancewith one embodiment.

FIG. 3B is a diagram that illustrates the removing of the proximityrelationship between the near field only RFID tag and the far fieldantenna such that the RFID device no longer functions as a far fieldRFID tag in accordance with one embodiment.

FIG. 3C is a diagram that illustrates the re-location of the near fieldonly RFID tag and the far field antenna to be in proximity to each otherto provide a magnetic coupling therebetween such that the near fieldonly RFID tag and the far field antenna again function in both the nearfield and the far field in accordance with one embodiment.

FIG. 3D is a diagram of a decoupled near field only RFID tag and a farfield antenna located in proximity to provide a capacitive couplingtherebetween such that the near field RFID tag and the far field antennafunction in both the near field and the far field in accordance with oneembodiment.

FIG. 3E is a diagram that illustrates the removing of the proximityrelationship between the near field only RFID tag and the far fieldantenna such that the RFID device no longer functions as a far fieldRFID tag in accordance with one embodiment.

FIG. 3F is a diagram that illustrates the re-location of the near fieldonly RFID tag and the far field antenna to be in proximity to each otherto provide a capacitive coupling therebetween such that the near fieldonly RFID tag and the far field antenna again function in both the nearfield and the far field in accordance with one embodiment.

FIG. 4A is an illustration of a conventional manufacturing process usedto create an RFID tag applied to an item.

FIGS. 4B, 4C and 4D are illustrations of various manufacturing processeswhere the manufacturing of a near field only RFID tag and a far fieldantenna are decoupled in accordance with several embodiments.

FIG. 4E is an illustration of a decoupled manufacturing process inaccordance with several embodiments.

FIG. 5 is a cross sectional view of one implementation of a decouplednear field only RFID tag and far field antenna as affixed to an item inaccordance with one embodiment.

FIG. 6 is a cross sectional view of another implementation of adecoupled near field only RFID tag and far field antenna as affixed toan item in accordance with one embodiment.

FIG. 7 is a cross sectional view of a further implementation of adecoupled near field only RFID tag and far field antenna as affixed toan item in accordance with one embodiment.

FIG. 8 is a cross sectional view of another implementation of adecoupled near field only RFID tag and far field antenna as affixed toan item in accordance with one embodiment.

FIG. 9 is a cross sectional view of another implementation of adecoupled near field only RFID tag and far field antenna as affixed toan item including an air gap maintained between the near field tag andthe far field antenna in accordance with one embodiment.

FIG. 10 is an illustration of a portion of an item packaging in which afar field antenna is formed on a surface of the item packaging inaccordance with one embodiment.

FIGS. 11-13 are illustrations of example items to incorporate RFIDtagging devices wherein the far field antenna design is incorporatedinto the product label design in accordance with several embodiments.

FIG. 14 is a cross sectional view of another implementation of adecoupled near field only RFID tag and far field antenna as affixed toan item in accordance with one embodiment.

FIG. 15 is an illustration of a portion of an item packaging in which afar field antenna is formed on a surface of the item packaging inaccordance with a variation of the embodiment of FIG. 10.

FIG. 16 is one embodiment of the portion of the item packaging of FIG.15 including a near field only RFID tag capacitively coupled to the farfield antenna.

FIG. 17 is a flowchart of the steps performed in one or moremanufacturing methods in accordance with several embodiments.

FIG. 18 is an illustration of an RFID sensor system in which a nearfield only RFID tag is decoupled with a far field antenna in accordancewith some embodiments.

FIG. 19 is an illustration of the RFID sensor system of FIG. 18 in whichthe near field only RFID tag is moved relative to the far field antennato be coupled with the far field antenna in accordance with someembodiments.

FIG. 20 is an illustration of the RFID sensor system of FIG. 18 in whichthe near field only RFID tag is moved relative to the far field antennato again be decoupled with the far field antenna in accordance with someembodiments.

FIG. 21 is an illustration of the RFID sensor system of FIG. 18 in whichan antenna of the reader is within a near field in accordance with someembodiments.

FIGS. 22-24 provide exemplary illustrations of integrated couplingstructures in which one or both of the near field only RFID tag and thefar field antenna are selectively movable to couple and decouple thenear field only RFID tag and the far field antenna in an RFID sensorsystem in accordance with some embodiments.

FIGS. 25-27 provide exemplary illustrations of coupling structuresimplemented as one or more discrete and non-integrated components inwhich one or both of portions containing the near field only RFID tagand the far field antenna are selectively movable to couple and decouplethe near field only RFID tag and the far field antenna in an RFID sensorsystem in accordance with some embodiments.

FIG. 28 is an illustration of an RFID device in which a far fieldantenna may be selectively moved into position to couple with one of twonear field only RFID tags for use in an RFID sensor system in accordancewith some embodiments.

FIG. 29 is an illustration of an RFID device in which a near field onlyRFID tag may be selectively moved into position to couple with one oftwo far field antennas for use in an RFID sensor system in accordancewith some embodiments.

FIG. 30 is an illustration of an RFID device in which a far fieldantenna may be selectively moved into position to couple with none orone of two near field only RFID tags for use in an RFID sensor system inaccordance with some embodiments.

FIG. 31 is an illustration of an RFID device in which a far fieldantenna may be selectively moved into position to couple with none orany one of a plurality of near field only RFID tags for use in an RFIDsensor system in accordance with some embodiments.

FIG. 32 is an illustration of an RFID device in which a near field onlyRFID tag may be selectively moved into position to couple with none orany one of a plurality of far field antennas for use in an RFID sensorsystem in accordance with some embodiments.

FIG. 33 is an illustration of an RFID device in which a far fieldantenna may be selectively moved into position to couple with two nearfield only RFID tags at the same time for use in an RFID sensor systemin accordance with some embodiments.

FIG. 34 is an illustration of an RFID device in which a near field onlyRFID tag may be selectively moved into position to couple with two farfield antennas at the same time for use in an RFID sensor system inaccordance with some embodiments.

FIG. 35 is a flowchart illustrating the steps involved in an RFID sensorsystem in accordance with some embodiments.

FIG. 36 is a functional block diagram of components of an RFID readerand controller in accordance with some embodiments.

Corresponding reference characters indicate corresponding componentsthroughout the several views of the drawings. Skilled artisans willappreciate that elements in the figures are illustrated for simplicityand clarity and have not necessarily been drawn to scale. For example,the dimensions of some of the elements in the figures may be exaggeratedrelative to other elements to help to improve understanding of variousembodiments of the present invention. Also, common but well-understoodelements that are useful or necessary in a commercially feasibleembodiment are often not depicted in order to facilitate a lessobstructed view of these various embodiments of the present invention.

DETAILED DESCRIPTION

The following description is not to be taken in a limiting sense, but ismade merely for the purpose of describing the general principles ofexemplary embodiments. The scope of the invention should be determinedwith reference to the claims.

Reference throughout this specification to “one embodiment,” “anembodiment,” or similar language means that a particular feature,structure, or characteristic described in connection with the embodimentis included in at least one embodiment of the present invention. Thus,appearances of the phrases “in one embodiment,” “in an embodiment,” andsimilar language throughout this specification may, but do notnecessarily, all refer to the same embodiment.

According to several embodiments, the design of the near field RFID tagcomponent and the far field antenna of a typical RFID tag is decoupled.For example, in one embodiment, the design of the near field RFID tagcomponent is independent of the design of the far field antenna thatwill be used together with the near field RFID tag component. In someforms, this will allow a vendor to design or select the best or mostcost effective near field only RFID tag without regard for the design ofthe far field antenna, and vice versa. Furthermore, when designing RFIDtags according to some embodiments, a vendor can use a single near fieldonly RFID tag for all uses, which leads to economies of scale loweringthe cost of tagging items to the vendor. Additionally, the design of thefar field antenna is simplified when it does not have to be integratedinto the same substrate package as the near field only RFID tag. Forexample, according to some embodiments, a near field only RFID tag thatdoes not include a far field antenna and does not function as a farfield RFID tag is mass produced by a tag manufacturer and purchased bythe item designer and/or manufacturer who designs, manufactures, or hasmanufactured the far field antenna which is substantially tuned to theitem. In many cases, the result is a cost effective and efficient RFIDtag that functions as both in the near field tag and the far field andis substantially tuned to the item to be tagged.

Generally, referring to FIGS. 1-17 and corresponding description,various RFID devices having a decoupled near field only RFID tag and farfield antenna and related methods according to some embodiments aredescribed. Additionally, referring to FIGS. 18-36, RFID sensors, systemsand methods are described in which RFID devices with decoupled nearfield only RFID tags and far field antennas are used to implement RFIDsensors in accordance with some embodiments.

Referring first to FIG. 1, a diagram is shown of the basic components ofan RFID system 100 including a passive RFID tag 102 and a tag reader 106as is conventionally known. The RFID tag 102 is formed on a substrateand includes an integrated circuit or chip (not shown) for storing andprocessing information, modulating and demodulating a radio-frequency(RF) signal, and other specialized functions. The RFID tag 102 alsoincludes a tag antenna 104. In a passive system, the reader 106 includesa reader antenna 108 and transmits a modulated radio frequency (RF)signal 110 to the RFID tag 102. The tag antenna 104 receives the RFsignal and forms an electric and magnetic field from which the RFID tag102 draws power for the integrated circuit. The integrated circuit thencauses the RFID tag 102 to modulate a backscatter RF signal 112 back tothe tag reader 106, the RF signal containing information encoded in thememory of the RFID tag 102. This is referred to as backscattering inthat a portion of the energy transmitted by the reader 106 is reflectedby the tag antenna 104 and modulated with data. Both the RFID tag 102and the tag reader 106 are transponders. The functionality and operationof the system 100 of FIG. 1 is well known.

Most RFID tags designed for use in enterprise supply chain managementare designed as both near field and far field RFID tags, i.e., they aredesigned to operate in both the near field and the far field. Asunderstood in the art, the near field and the far field are a functionof the frequency of electromagnetic energy received at an RFID tag(e.g., from interrogation signals transmitted by RFID readers) andbackscattered by the RFID tag. The near field is the region about thetag 102 relative to the reader antenna 108 where the reader antenna 108and the tag 102 are coupled within one full wavelength of the carrierwave; however, in many practical applications, the near field is withinone half wavelength of the carrier wave. The near field signal decays asthe cube of the distance r from the reader antenna (1/r³). The far fieldis that region about the tag 102 relative to the reader antenna 108where the reader antenna 108 and the tag 102 are coupled beyond one fullwavelength of the carrier wave. The far field signal decays as thesquare of the distance r from the reader antenna (1/r²). In a typicalultra-high frequency (UHF) RFID system where the carrier frequency is inthe range of 860-960 MHz, the effective near field is the region up toapproximately 10-15 centimeters from the reader antenna 108, whereas thefar field is the region from approximately 15-40 centimeters and beyondthe reader antenna 108. In many cases, the reader 106 can read in thenear field up to about 15 centimeters away, whereas depending on the tagantenna, the reader 106 can read in the far field up to about 20-30 feetor more away. For example, with the use of semi-passive tags, the farfield may reach up to 100 feet or more. These features are also wellknown in the art. It is understood that the near field only tag 200 maybe designed to operate with reader antennas operating at a variety offrequencies, such as low frequency (LF) at 125-134 kHz, high frequency(HF) at 13.56 MHz, ultra high frequency (UHF) at 860-960 MHz, microwavefrequencies at 2.4 and 5.8 GHz, for example.

Another way to express a distinction between near field and far fieldcommunication is as follows, which is understood in the art. Givenelectromagnetic energy at a given frequency transmitted to a particularantenna element of the RFID tag, the near field is that portion of theregion about the tag in which the electric field of oscillatingelectrons of the antenna element/s are not stripped off due to theoscillating energy. Thus, the far field is that region about the tag inwhich the electric field is stripped from the antenna element/s. Thatis, consider the viewpoint of a single stationary electron which haselectric field lines radiating outward. That electron is moved oraccelerated by the received energy oscillating at a frequency. As theelectron moves back and forth, the electron's electric field lines willtry to catch up with the electrons new location but they are limited bythe speed of light on how fast they can catch up. This creates a rippleeffect in the electric field. At low frequencies, the near field is verylarge because there is very little acceleration of the electronresulting in little rippling of the electric field lines. With littleripple effect, then there is little propagation and what remains ismostly near field. At ultra high frequency the electrons areaccelerating back and forth creating a ripple effect in one directionand the back the other direction. This produces a sinusoidalelectromagnetic wave that begins to propagate through space. The nearfield is generally ½ wave length within the region where the electricfield lines can keep up with the electrons. This is the area where theelectric field crosses from positive to negative and back again. Thus,generally, the faster the electrons are oscillated by the receivedsignals from the reader, the shorter distance covered by the near fieldand the far field. FIGS. 18-20 provide simplified illustrations of thenear field and the far field relative to an RFID tag device and an RFIDreader.

In a typical enterprise supply chain management application, it isdesired that the RFID tag 102 be a near field and far field tag to allowit to be read from the near field and the far field. The typical RFIDtag 102 is an integrated package that includes an integrated circuitencoding an identification and a loop to give it the near field tagfunctionality. However, since this loop does not respond to the farfield, the integrated package also includes a far field antenna or tagantenna that gives it the far field tag functionality. The typical farfield antenna is a dipole antenna. The far field antenna is usuallyelectrically coupled to the near field loop and the integrated circuitin most integrated RFID tags, but in some cases, the far field antennais not electrically coupled to the near field loop or the integratedcircuit and relies on inductive or magnetic coupling. The near fieldloop and the far field antenna are commonly printed or etched on thesubstrate as part of the same printing/etching process and then theintegrated circuit is carefully placed thereon. The resulting integrateddevice is referred to as an RFID inlay.

There are several problems with this integrated design of the RFID tag102. First, it is well known that dielectric properties of the item thatthe RFID tag is attached to affect the performance of the far fieldantenna. That is, the dielectric of the item may change the resonatefrequency of the inlay's far field antenna. In order for the RF signalto get to the integrated circuit there has to be an impedance matchingbetween the far field antenna, the loop and the chip. The more the farfield antenna is detuned, the greater the impedance is mismatched. Thetag's performance degrades as the impedance mismatch increases until thetag stops working. Certain products in a retail environment are known topossess dielectric qualities that make it challenging to design goodperforming RFID tags. For example, the cleanser Pine-Sol® results in thedetuning of the far field antenna. Knowing this problem, the vendor candesign the RFID tag 102 to tune the far field antenna so that the farfield antenna will match the impedance with the chip and the loop whenapplied to the problem item. Typically, the length of the far fieldantenna is altered, e.g., shortened, to tune the antenna properly to theitem it will be attached. However, due to the integration of the nearfield RFID tag and the far field antenna, in changing the far fieldantenna to be tuned to a particular item, the supplier will require adifferent integrated RFID tag for different products. Thus, in someembodiments, the design of the near field tag and the far field antennaneed to account for each other. Again, this will cause suppliers to needto stock several different integrated RFID tags suitable for variousproducts.

Referring briefly to FIG. 4A, a conventional manufacturing process isshown for creating an RFID tag 402 to be applied to an item. The RFIDtag 402 is first designed as an integration of a near field RFID tag 404and a far field antenna 406 as described above (e.g., the near fieldloop and far field antenna are printed or etched on a substrate and theintegrated circuit is positioned thereon). The design of the near fieldRFID tag 404 and the far field antenna 406 must account for each otherand for the dielectric properties of the item 408 it will eventually beaffixed to. Once the RFID tag 402 design is complete, the RFID tags aremanufactured by or for the supplier and then applied to the item 408. Insome cases, the RFID tag 402 is located on the under side of an adhesivesticker or other label and adhered to the item. In other cases, the RFIDtag 402 integrated into the item or it's packaging during manufacturingof the item 408. In these cases, due to the harsh environment ofmanufacturing of the item (for example, due to printing, heat, highspeed, etc.), it is common to damage the RFID tag 402. This makes itmore difficult for a supplier or vendor to certify that the RFID tagwill operate at an acceptable read rate. Finally, once the RFID tag 402is added or affixed to the item 408, the result is a tagged item 410.

As a solution to one or more of the problems above and/or otherproblems, in some embodiments, the manufacturing and design of the nearfield RFID tag component is decoupled from or independent of themanufacturing and design of the far field antenna. In some embodiments,the goal is not to design a fully integrated and packaged RFID tagincluding both a near field RFID tag and the far field antenna on thesame substrate. In several embodiments, a universal tag can be designedusing only a simple pre-manufactured near field only RFID tag and aseparate and independently designed electrically conductive element thatwill function as the far field antenna. Since the design of the twocomponents will be separate, in some embodiments, the same near fieldonly RFID tag can be used for all items or products to be tagged. Toaccount for the varying degree of de-tuning effect caused by certainitems or products, only the conductive element need be specificallydesigned. For example, in the case of a conductive element in the formof a simple wire, the length of the wire can be shortened to match theimpedance of the far field antenna to the integrated circuit.

FIG. 2A illustrates a simple pre-manufactured RFID tag 201 including anintegrated circuit 204 (or chip 204), a loop 202 and a tag antenna 203(far field antenna) formed on a substrate 206 as is conventionallyknown. In one example, the RFID tag 201 is the Impinj® Paper Clip™commercially available from Impinj, Inc. The RFID tag 201 functions asboth a near field and far field RFID tag, i.e., it functions in and maybe read from both the near field and the far field.

FIG. 2B illustrates a near field only RFID tag 200 including theintegrated circuit 204 (or chip 204) and the loop 202 formed on thesubstrate 206, but lacking the tag antenna 203, in accordance withseveral embodiments. In one embodiment, the near field only RFID tag 200may be formed by removing the tag antenna 203 of the device of FIG. 2A.In another embodiment, the near field only RFID tag may bepre-manufactured to not include the tag antenna 203. According toseveral embodiments, the near field only RFID tag 200 does not functionas a far field RFID tag, i.e., on its own, it can not be read in the farfield by a tag reader 106. In preferred embodiments, the loop 202 isdesigned, shaped and/or configured to be suitable for use with a farfield antenna to be electromagnetically and/or electrically coupledthereto. This is in contrast to known pre-manufactured near field onlyRFID tags that are designed for use only in the near field. For example,the Impinj® Button™ is a near field only tag that has a chip with acircular loop and is not designed to be used with a far field antenna.Thus, this device is not designed for efficient coupling with a farfield antenna. In some embodiments, the loop 202 is designed without atag antenna 203 or far field antenna, but so that as described in moredetail below, it will be later coupled to a separate tag antenna or afar field antenna in a separate manufacturing process. In someembodiments, the loop is designed in a generally rectangular shape withtwo elongated sides that assist in the generation of current from beingmagnetically coupled to a tag antenna.

It is understood that the near field only tag 200 may be designed tooperate with reader antennas operating at a variety of frequencies, suchas low frequency (LF) at 125-134 kHz, high frequency (HF) at 13.56 MHz,ultra high frequency (UHF) at 860-960 MHz, microwave frequencies at 2.4and 5.8 GHz, for example.

FIG. 2C is a diagram of a near field only RFID tag 205 including theintegrated circuit 204 (or chip 204), the loop 202 and conductors 208and 210 formed on the substrate 206 to allow for capacitive couplingwith a far field antenna according to another embodiment. In operation,each of the conductors 208 and 210 can function as a first electrode ofa capacitor formed between itself and a far field or tag antenna, wherea portion of the far field antenna forms the second electrode of thecapacitor. Electromagnetic energy from the tag reader 106 causes thevoltage on the far field antenna (particularly at its end) to oscillatebuilding a charge. This creates an oscillating potential difference ateach elongated side of the tag 205, which causes a current to flow aboutthe loop 202. This flowing current allows the chip 204 to operate and inturn, the far field antenna capacitively coupled to the tag 205 totransmit an encoded backscattered signal to the tag reader 106.

In one embodiment, the near field only RFID tag 205 may bepre-manufactured. According to several embodiments, the near field onlyRFID tag 205 does not function as a far field RFID tag, i.e., on itsown, it can not be read in the far field by a tag reader 106. Inpreferred embodiments, the loop 202 is designed, shaped and/orconfigured to be suitable for use with a far field antenna capacitivelycoupled thereto. In some cases, the width or thickness of the conductors208 and 210 is designed to ensure good capacitive coupling with the farfield antenna. This is also in contrast to known pre-manufactured nearfield only RFID tags that are designed for use only in the near field.For example, the Impinj® Button™ is a near field only tag that has achip with a circular loop. In some embodiments, the loop 202 is designedwithout a tag antenna 203 or far field antenna, but so that as describedin more detail below, it will be later coupled to a separate tag antennaor a far field antenna in a separate manufacturing process. In someembodiments, the loop is designed in a generally rectangular shape withtwo elongated sides that correspond to the elongated conductors 208 and210 to assist in generating a current traveling in the loop 202 viacapacitive coupling with the far field antenna.

Referring next to FIG. 3A, a simple diagram is shown of a decoupled nearfield only RFID tag 200 and a far field antenna 302 located inproximity. Due to the proximity of location, the near field only RFIDtag 200 is magnetically coupled to the far field antenna 302 such thatthe combination of the near field only RFID tag 200 and the far fieldantenna 302 function as a far field RFID tag in accordance with oneembodiment, e.g., the combination operates in both the near field andthe far field. That is, when the far field antenna 302 is magneticallyor inductively coupled to the near field only RFID tag 200, the devicebecomes visible to a far field RFID reader. In some embodiments, it isdesired that the center of the far field antenna 302 should be alignedwith a center of the near field loop 202. It is noted that the far fieldantenna 302 is one example of and may be generically referred to as aconductive element. In the illustrated embodiment, the far field antenna302 takes the form a simple metallic wire. That is, the far fieldantenna 302 is not printed or etched onto the substrate of the nearfield only tag 200. It is known that the magnetic coupling of a nearfield tag with a far field antenna results in a functioning near fieldand far field RFID tag; however, in contrast to prior attempts, the nearfield only RFID tag 200 and the far field antenna 302 are not integratedinto an inlay or substrate package. As is further described below,several coupling structures are provided to locate the near field onlyRFID tag and the far field antenna in close proximity in order to bemagnetically coupled. For example, in some embodiments, the near fieldonly RFID tag and the far field antenna are coupled in proximity (orthere is a proximity relationship defined therebetween), when a portionof the far field antenna 302 is contacting (electrically andmagnetically coupled to) or spaced apart and near (magnetically orcapacitively coupled to) a portion of the loop 202 of the near fieldonly RFID tag.

In some embodiments, the near field only RFID tag 200 is mass producedwithout consideration of the dielectric properties of the item to betagged, whereas the far field antenna is substantially tuned to the itemto be tagged. This decouples the manufacturing of the near field onlyRFID tag 200 and the far field antenna 302. In one embodiment, sinceonly the design (e.g., length) of the far field antenna 302 changes fordifferent items, then the vendor can purchase bulk quantities of thenear field RFID tag 200 for all items to be tagged, leading to economiesof scale. Furthermore, relative to the known integrated near field RFIDtag and far field antenna designs, since the far field antenna is notprinted or etched as done in the prior art and depending on the wiringused, there may be less metal to be etched or printed for the RFIDinlay, which leads to lower overall costs for the supplier to implementtagging. In some cases, when the far field antenna is integrated intothe printing of the product label having a conductive material such asmetal, there would be little additional cost in adding the far fieldantenna.

The far field antenna 302 may be implemented with a section of wire cutto a certain length. Thus, the vendor can purchase spools of wiring tobe used as the far field antenna 302, cutting the proper length to betuned for the frequencies in use and to also tune for the specific itemto be tagged. It is noted that in the case of some items, while the farfield antenna is tuned to the radio frequencies in use, additionaltuning may not be necessary to account for the dielectric properties ofthe item. Thus, a particular length or configuration of the far fieldantenna may be selected based on the dimensions of the item andfrequencies used without concern for the need to additionally tune thefar field antenna to account for the dielectric properties of the item.In one embodiment, the wire is then placed where the center of the wireslength is aligned with the center of the near field loop. Additionally,in some embodiments, the polarity of the far field antenna 302 and thenear field only RFID tag 200 needs to be aligned. Furthermore, sincethey are not integrated in a substrate design, the design of the nearfield only RFID tag 200 does not need to account for the design of thefar field antenna 302. It has been found that such a decoupled nearfield only RFID tag where the far field antenna 302 is tuned to the itemperforms as well or better than the conventional integrated near fieldtag and far field antenna approach.

The inlay supplier makes large production runs of a small near-fieldonly tags gaining economy of scale cost reductions. The tag is muchsmaller using less metal providing a material cost reduction. In someembodiments, the manufacturer uses the same process to tag all itemsreducing execution cost. By way of example, the manufacturer inventoriesone near field only RFID tag 200 and a spool of wire (to be used for theconductive element that will function as the far field antenna) reducingthe cost of production delays due to the correct tag being out of stock.The overall near and far field tag is tuned to the item so that itperforms well through the many read points in the supply chain reducingthe cost of inventory inaccuracies. Again, in some embodiments for usewith some items, additional tuning to account for dielectric propertiesmay not be needed.

For magnetic coupling between the near field RFID tag 200 and the farfield antenna 302 so that both will function as a far field tag, in someembodiments, the near field RFID tag 200 and the far field antenna 302need to be maintained a close distance, but not electrically coupledtogether. For example, they are coupled in proximity to each other, or aproximity relationship is defined therebetween. In one embodiment, thenear field only RFID tag 200 and the far field antenna 302 should bemaintained at a separation distance of no more than ¼ inch, or no morethan ⅛ inch, or in other cases, no more than 1/16 inch. In manyembodiments, the separation distance will be much less than 1/16 inch.In some embodiments, an air gap is maintained between the near fieldonly RFID tag and the far field antenna, whereas in other embodiments,an insulator or a non-electrically conducting material is locatedtherebetween to prevent electrical coupling and/or aestheticconsiderations. In other embodiments, the far field antenna 302 may bein physical or electrical connection with one or more of the near fieldonly tag 200, the integrated circuit 204 of the near field tag or theloop 202. In such cases, the far field antenna 302 and the near fieldtag 200 will be electrically coupled and still be magnetically coupled.This is another example of the far field antenna 302 and near field onlyRFID tag being coupled in proximity to each other, or with a proximityrelationship defined therebetween.

While in many embodiments, the far field antenna 302 is implemented as asimple wire, it is understood that the far field antenna may be anyconductive element and may have many different geometries. For example,the far field antenna may be implemented as a flat and straight strip orelongated sheet of electrically conductive material. In someembodiments, the far field antenna may be printed onto a surface of theitem or its packaging/label. In other embodiments, the far field antennamay be formed from a portion of the packaging of an item, such as ametallic or conductive lining of the packaging of the item. In otherembodiments, the far field antenna may be formed from or implemented onthe exterior label or printing on the item, such as conductive ink or afoil stamp formed on the item or a portion of the label for the item. Infurther variations, the far field antenna is not required to be straightas illustrated, but may be shaped or bent or round into different shapesor configurations. However the far field antenna is designed, it shouldbe adjustable to tune the far field antenna to the particular item thatis to be tagged; however, some items will not require additional tuningto account for the dielectric properties of the item. By allowing onlythe far field antenna to be varied, in some embodiments, all RFID tagscan be made using the same pre-manufactured near field only RFID tags.

In further embodiments, a coupling structure/s is provided to locate thenear field only RFID tag 200 and the far field antenna 302 for magneticcoupling (whether directly electrically contacting or not) and isdesigned to allow for the removal of the magnetic coupling, such asillustrated in FIG. 3B. That is, in a generic sense, a couplingstructure is provided that will allow for the removal of the proximityrelationship between the near field only RFID tag and the far fieldantenna. In other words, the far field antenna and the near field onlyRFID tag will be uncoupled in proximity. For example, a couplingstructure (not illustrated) allows for the removal of one or both of thenear field RFID tag 200 and the far field antenna 302 such that they areno longer magnetically (whether directly contacting or not) coupledtogether. This results in the conversion of the far field RFID tag backto a near field only RFID tag that can only be read in the near field,not the far field. That is, the RFID device no longer functions as a farfield RFID tag. In some embodiments, the coupling structure may helpmaintain a separation between the near field only RFID tag 200 and thefar field antenna 302.

In even further embodiments, as illustrated in FIG. 3C, the couplingstructure (not illustrated) is designed to allow the re-location of thenear field only RFID tag 200 and the far field antenna 302 to be inproximity to each other to provide a magnetic re-coupling therebetweensuch that the near field only RFID tag 200 and the far field antenna 302again function both as a near field and a far field RFID tag inaccordance with one embodiment. Thus, the proximity relationship betweenthe far field antenna 302 and the near field only RFID tag 200 that waspreviously removed, can be re-established. For example, the couplingstructure may be such that one or both of the near field only RFID tag200 and the far field antenna 302 are able to be re-located such thatboth the near field only RFID tag and the far field antenna are againmagnetically coupled together (whether electrically re-coupled or not).This results in the conversion of the near field only RFID tag back to anear and far field RFID tag. It is noted that in some embodiments, areplacement far field antenna and/or a replacement near field only RFIDtag may be used instead of repositioning the same components. Examplecoupling structures include portions of the item itself or its packagingor label, insulating or non-electrically conducting separators,removable stickers or labels, etc. Further details of such couplingstructures are described in more detail below.

It is noted that in some embodiments, other non-traditional designs maybe used for the near field RFID tag. For example, in one alternative,chipless near field RFID tags are used instead of the traditional nearfield tags.

Next referring to FIGS. 3D-3F, diagrams similar to those of FIGS. 3A-3Care shown that illustrate the removable coupling in proximity of adecoupled near field only RFID tag 205 such as shown in FIG. 2C and thefar field antenna 302 with capacitive coupling therebetween inaccordance with one embodiment. FIG. 3D illustrates the capacitivecoupling, FIG. 3E illustrates the dynamically removal of the capacitivecoupling and FIG. 3F illustrates the ability to re-establish thecapacitive coupling.

Generally, the embodiments of FIGS. 3D-3F operate similarly, and havesimilar advantages and benefits as described in connection with FIGS.3A-3C; however, the proximity coupling is in the form of capacitivelycoupling. Thus, much of the detailed description relating to FIGS. 3A-3Cis not repeated and attention is given to the nature of the capacitivecoupling.

To affect capacitive coupling, in one embodiment, the near field onlyRFID tag 205 is coupled in a spaced relationship to one end 304 of thefar field antenna 302. In the illustrated embodiment, the end 304 isbent relative to the bulk of the far field antenna 302, although this isnot required. In operation, the voltage at the end 304 oscillates due tothe received electromagnetic energy from the tag reader 106. In someembodiments, the end 304 and the conductor 208 of the near field onlyRFID tag 205 form two electrodes of a capacitor. As the voltageoscillates at the end 304 building at charge, this creates anoscillating potential difference at the elongated side of the tag 205,which causes a current to flow about the loop of the near field onlyRFID tag 205. This flowing current allows the chip to operate and inturn, the far field antenna 302 capacitively coupled to the tag 205 totransmit an encoded backscattered signal to the tag reader 106.

When the end 304 of the far field antenna 302 is capacitively coupled tothe near field only RFID tag 205, the device becomes visible to a farfield RFID reader. In some embodiments, it is desired that one end ofthe far field antenna 302 should be aligned with a conductor (adapted toform a capacitor electrode) of the near field only RFID tag 205. FIG. 3Dprovides another example of the near field only RFID tag and the farfield antenna being coupled in proximity, or a proximity relationshipbeing defined therebetween, when a portion of the far field antenna 302is spaced apart and near (capacitively coupled to) a portion of the loopof the near field only RFID tag.

Referring next to FIGS. 4B, 4C and 4D, simplified representations ofmanufacturing processes are shown where the manufacturing of a nearfield only RFID tag and a far field antenna are decoupled in accordancewith several embodiments.

In contrast to that shown in FIG. 4A, and referring first to theembodiment of FIG. 4B, as a separate manufacturing process, the nearfield only RFID tag 200 (or 205) and the item 408 are coupled togetherwithout the far field antenna 302. For example, a standardpre-manufactured near field only RFID tag 200 is coupled to a surface ofthe item 408 at a desired location or desired surface of the item. Insome cases, the near field only RFID tag 200 is implemented on interiorsurface of the item or its packaging. In other cases, the near fieldonly RFID tag 200 is implemented within the item or its packaging, suchas between material layers or between layers of corrugated cardboardpackaging, by way of a few examples. It is understood that there may bemany other examples. At this point, integrated unit 412 includes theitem 408 and the near field only RFID tag 200. In one embodiment, theunit 412 will be designed to include a location or structure that willbe adapted to receive the far field antenna 302. In one form, a mountinglocation is provided at a desired location proximate the near field onlyRFID tag 200 such that the near field only RFID tag 200 and the farfield antenna 302 are coupled in proximity to each other, or a proximityrelationship is established therebetween. As used herein, the termproximate refers to two components that very close or near to eachother, and can cover a physical contact or connection between the twocomponents. Next, as a separate manufacturing process, depending on thenature of the item 408, the far field antenna 302 that is tuned to theitem 408 is added to the unit 412 to result in the tagged item 414.Typically, the far field antenna is designed and tuned to the item 408prior to this step. For example, using the near field only tag and thefar field antenna, through trial and error, the far field antenna can betuned to the dielectric properties of the particular item. It is notedthat in some embodiments, the far field antenna 302 does not need to beadditionally tuned to account for the dielectric properties of the item,for example, if the item is simply a cardboard box. In some embodiments,the far field antenna 302 is applied as a sticker to an exterior surfaceof the unit 412 that is proximate to the near field only RFID tag 200such that the far field antenna 302 will be aligned as intended with thenear field only RFID tag 200 to ensure good proximity coupling(electric, magnetic or capacitive). In one embodiment, the couplingstructure/s that couples the near field RFID tag 200 and the far fieldantenna 302 is designed so that one of the near field RFID tag 200 andthe far field antenna 302, and the proximity relationship therebetween,are allowed to be removed from the tagged item 414, effecting thediagram of FIG. 3B or FIG. 3E. In some embodiments, the assembly of thetagged item 414 is done by the manufacturer and/or the packager of theitem 408, such as shown in FIG. 4E.

FIG. 4C illustrates an alternative embodiment in which as a separatemanufacturing process, the far field antenna 302 and the item 408 arecoupled together without the near field only RFID tag 200 (or 205),where the far field antenna is already tuned to the item 408 (if tuningis needed for the item 408) in a prior manufacturing process. Forexample, the far field antenna 302 is coupled to a surface of the item408 at a desired location or desired surface of the item. In some cases,the far field antenna 302 is implemented on interior surface of the itemor its packaging. In other cases, the far field antenna 302 isimplemented within the item or its packaging, such as between materiallayers or between layers of corrugated cardboard packaging, by way of afew examples. In some forms, the far field antenna 302 is implemented aspart of or from a part of a conductive material forming part of the itemor its packaging, such as a conductive ink or foil stamp. For example,in one embodiment, the far field antenna 302 is formed from a portion ofa conductive label. It is understood that there may be many otherexamples. At this point, integrated unit 416 includes the item 408 andthe far field antenna 302 but not the near field only RFID tag 200. Inone embodiment, the unit 416 will be designed to include a location orother coupling structure that will be adapted to receive the near fieldonly RFID tag 200. In one form, a mounting location is provided at adesired location proximate the far field antenna 302 such that the nearfield only RFID tag 200 and the far field antenna 302 will be coupled inproximity to each other, or a proximity relationship will be establishedtherebetween. Next, as a separate manufacturing process, the near fieldonly RFID tag 200 is added or affixed to the unit 416 to result in thetagged item 418. In some embodiments, the near field only RFID tag 200is applied as a sticker to an exterior surface of the unit 416 that isproximate to the far field antenna 302 such that the near field RFID tag200 will be aligned as intended with the far field antenna 302 to ensuregood proximity coupling (electric, magnetic or capacitive). In oneembodiment, the coupling structure/s that couple the near field onlyRFID tag 200 and the far field antenna 302 is designed so that one ofthe near field only RFID tag 200 and the far field antenna 302, and theproximity relationship therebetween, are allowed to be removed from thetagged item 418, effecting the diagram of FIG. 3B or FIG. 3E. In someembodiments, the assembly of the tagged item 418 is done by themanufacturer and/or the packager of the item 408, such as shown in FIG.4E.

FIG. 4D illustrates a further manufacturing process in which while thenear field only RFID tag 200 (or 205) and the far field antenna 302 areseparately and independently designed, they are packaged together asunit 420 prior to being coupled in proximity to the item 408. However,in contrast to that shown in FIG. 4A, the near field only RFID tag 200and the far field antenna 302 are independently designed and notintegrated in the same manufacturing process and/or on the samesubstrate. In several embodiments, a coupling structure is provided tomaintain the near field only RFID tag 200 and the far field antenna 302in close proximity to ensure magnetic or capacitive coupling withoutelectrical coupling, whereas in other embodiments, the near field onlyRFID tag 200 and the far field antenna 302 are in electrical connectionand magnetically coupled. Such coupling structure does not integrate thenear field only RFID tag 200 and the far field antenna 302 such that thedesign of one at least in part does not dictate the design of the otheras is the case with all known prior attempts to integrate a near fieldRFID tag and far field antenna into a near and far field tag on asubstrate. For example, in one embodiment, the pre-manufactured nearfield only RFID tag 200 is applied to an under surface of a sticker orother coupling structure, then the far field antenna 302 predesigned tobe tuned to the item 408 (to the extent additional dielectric tuning isneeded) is also applied to the under surface (or top or other surface)of the sticker. This combination unit 420 including a couplingstructure, the near field only RFID tag 200 and the far field antenna302 and is then applied to the item 408 to result in the tagged item422. In one embodiment, the unit 420 is designed so that one of the nearfield only RFID tag 200 and the far field antenna 302, and the proximityrelationship therebetween, are allowed to be removed from the unit 420,effecting the diagram of FIG. 3B or FIG. 3F. In some embodiments, theassembly of the tagged item 418 is done by the manufacturer and/or thepackager of the item 408, such as shown in FIG. 4E.

It is noted that by allowing for the independent design and manufactureof the near field RFID tag and the far field antenna, the design of eachcan be optimized without concern for the other, at least with respect todesign to account for the dielectric properties of the item to betagged. In some embodiments, the near field only RFID tag is at leastdesigned so that the near field loop of the near field only RFID tag canefficiently couple to the far field antenna. This allows a best of bothworlds device, as opposed to conventional approaches that integrate anear tag and a far field antenna into one substrate package such thatthe device of both components can result in a compromise due to thelevel of integration.

It is further noted that the item 408 to be tagged may generally be anyliving or non-living object, package, material, structure, animal,plant, person, etc. In a commercial manufacturing, distribution, retailenvironment, the item 408 may be a portion of or a whole of a product,object, label, product label, product packaging, carton, container,pallet, etc. It is understand that these example lists of potentialitems to be tagged is provided by way of example and is not anexhaustive list of all items that could be tagged in accordance with oneor more embodiments. In accordance with several embodiments, the item408 to be tagged is an individual item, or the packaging for anindividual item, to be presented for sale in a commercial setting.

Referring next to FIG. 4E, an illustration is shown of a decoupledmanufacturing process in accordance with several embodiments. Initially,a near field only RFID tag 450 (e.g., near field only RFID tags 200,205) is obtained from an RFID tag manufacturer. The near field only RFIDtag 450 is mass produced and item neutral. That is, the near field onlyRFID tag 450 has not been designed to account for the dielectricproperties of any particular item to be tagged. Like those describedabove, the near field only RFID tag 450 does not include a tag or farfield antenna, and thus; is only readable in the near field of theoperating reader wavelengths. Since the near field only RFID tag 450does not have to be tuned or otherwise account for a particular item,the cost of the near field only RFID tag 450 can be minimized. Forexample, there is less metal used in the near field only RFID tag 450.Additionally, the RFID tag manufacturer need only manufacture, and theitem manufacturer need only obtain, one version of the near field onlyRFID tag 450 produced in mass for all items to be tagged.

The item manufacturer obtains the near field only RFID tag 450 and usesit together with a far field antenna 452 (generically, a conductiveelement) tuned for the particular item 454 to be tagged (to the extenttuning is needed) to produce a tagged item 456. Since the far fieldantenna 452 is designed by the item manufacturer, and may often beimplemented as part of the packaging design, the cost of the overallRFID tag can be reduced and item-level tagging in a commercial retailenvironment is achievable. By tuning the far field antenna 452 to theitem, the item manufacturer is able to create tagged items that will bewithin acceptable read requirements required by retailers or customersof manufacturer vendors. It has been found that there is greatvariability in the performance of RFID tags when implemented on finalitems that RFID tag manufacturers are not in the best position tounderstand. Thus, in some embodiments, the location of the tuningfunction is provided to the entity that is in the best position tounderstand and know the final intended use of the tag. Additionally, asillustrated in FIGS. 5-16, the design of the far field antenna 452 maybe developed together with the item or its packaging. Severalembodiments of the decouple the manufacturing and design of the nearfield RFID tag functionality and the far field antenna functionality ina way that can lead to efficiencies in manufacturing costs andimprovements in read rates.

Referring next to FIG. 5, a cross sectional view is shown of oneimplementation of a decoupled near field only RFID tag 200 and far fieldantenna 302 as affixed to a portion 502 of an item in accordance withone embodiment. Alternatively, near field only RFID tag 205, 450 orother near field only RFID tag could be used. The portion 502 of theitem may be the item itself or the packaging of the item. In theillustration, the near field only RFID tag 200 is coupled to an interiorsurface 504 of the portion 502 with coupler 506, which may be embodiedas a sticker or other structure. The far field antenna 302 isillustrated as being coupled to the exterior surface 508 of the portion502 of the item. In one embodiment, the far field antenna 302 is coupledto the portion 502 with couplers 510, 512. It is noted that in someembodiments, one or more of the couplers 506, 510 and 512 should beinsulating to prevent electrical coupling of the far field antenna andthe near field only RFID tag. Other embodiments may allow the far fieldantenna 302 and the near field only RFID tag 200 to be electricallyconnected and magnetically coupled. In one embodiment, the couplers 510,512 take the form of a sticker. Thus, a coupling structure is providedto couple the far field antenna 302 and the near field RFID tag 200 tothe item in close proximity to ensure magnetic coupling therebetween (orcapacitive coupling in the case of the near field only RFID tag 205). Inalternative embodiments, the coupling structure provides an air gapseparation between the far field antenna 302 and the near field onlyRFID tag 200. The portion 502 is selected to have a thickness to allowthe close coupling, e.g., less than about ¼ inch, less than about ⅛inch, or less than about 1/16 inch. Alternatively, in one embodiment,one or both of the couplers 510 and 512 are not needed and the far fieldantenna 302 is applied or printed directed to the surface 508. In thiscase, the surface 508 and the portion 502 become the coupling structureto maintain the far field antenna and the near field only RFID tag inclose proximity for electrical, magnetic and/or capacitive coupling. Inthe illustrated embodiment, the coupler 512 is removable from thecoupler 510 to allow the far field antenna 302 to be later removeddepending on the use of the RFID tag. For example, a user could pull atab 514 to remove the coupler 512 and the far field antenna 302 from thecoupler 510 and the portion 502. Removal of the coupler 512 results inthe far field antenna being magnetically decoupled from the near fieldonly RFID tag such that the remaining RFID tagged item will onlyfunction as a near field tag. That is, the proximity relationshipbetween the far field antenna and the near field only RFID tag isremoved. It is noted that the coupler 510 may not be present or may be alayer of adhesive in other embodiments. In another alternative, thecoupler 512 may simply take the form of an outer packaging wrap, such asa plastic or paper (preferably an insulating material) wrap having thefar field antenna attached thereto, but removable when the plastic wrapis removed.

Referring next to FIG. 6, a cross sectional view is shown of anotherimplementation of a decoupled near field only RFID tag 200 and far fieldantenna 302 as affixed to a portion 602 of an item in accordance withone embodiment. In another embodiment, near field only RFID tag 205, 450or other near field only RFID tag could be used. The portion 602 of theitem may be a portion of the item itself or the packaging of the item.In the illustration, the near field only RFID tag 200 is embedded withinlayers of the portion 602, e.g., between layers of a corrugatedcardboard structure, with coupler 604, which may be embodied as asticker or other insulating structure. The far field antenna 302 isillustrated as being coupled directly to the exterior surface 606 of theportion 602 of the item with coupler 608. In one embodiment, the coupler608 takes the form of a sticker. Thus, in some embodiments, a couplingstructure is provided to couple the far field antenna 302 and the nearfield only RFID tag 200 to the portion 602 of the item in closeproximity to ensure magnetic coupling therebetween without electricalcoupling (or capacitive coupling in the case of the near field only RFIDtag 205). The portion 602 is selected to have a thickness to allow theclose coupling needed for magnetic or inductive coupling, e.g., lessthan about ¼ inch, less than about ⅛ inch, or less than about 1/16 inch.Again, in some embodiments, the far field antenna 302 and the near fieldonly RFID tag 200 are electrically and magnetically coupled. Inalternative embodiments, the coupling structure provides an air gapseparation between the far field antenna 302 and the near field onlyRFID tag 200. Alternatively, in one embodiment, the far field antenna302 is adhered or printed to the exterior surface 606 such that thecoupler 608 is not needed. In this case, the exterior surface 606 andthe portion 602 become the coupling structure to maintain the far fieldantenna and the near field only RFID tag in close proximity forelectrical, magnetic and/or capacitive coupling. Although notspecifically illustrated, in some embodiments, the coupler 608 and thefar field antenna 302 may be adapted to be removed from the portion 602to allow the far field antenna 302 to be later removed depending on theuse of the RFID tag. For example, a user could pull on a tab to removethe coupler 609 and the far field antenna 302. This removal will resultin the far field antenna being magnetically decoupled from the nearfield only RFID tag such that the remaining RFID tagged item will onlyfunction as a near field tag and no longer function as a far field tag.That is, the proximity relationship (whether electrical, magnetic and/orcapacitive) between the far field antenna and the near field only RFIDtag is removed. In one alternative, the coupler 608 may simply take theform of an outer packaging wrap, such as a plastic wrap, shrink wrap orpaper wrap having the far field antenna attached thereto, but removablewhen the wrap is removed.

FIG. 7 is a cross sectional view of a further implementation of adecoupled near field only RFID tag 200 and far field antenna 302 asaffixed to a portion 702 of an item in accordance with one embodiment.In another embodiment, near field only RFID tag 205, 450 or other nearfield only RFID tag could be used. The portion 702 of the item may be aportion of the item itself or the packaging of the item. In theillustration, the near field only RFID tag 200 is coupled to an exteriorsurface 704 of the portion 702 with the coupler 506, which may beembodied as a sticker or other structure. The far field antenna 302 isillustrated as being coupled to the interior surface 706 of the portion702 of the item, e.g., it is printed or formed or otherwise adhered tothe interior surface 706. In an alternative embodiment, the far fieldantenna 302 is coupled to the interior surface 706 with a coupler, suchas a sticker or other structure. Thus, in some embodiments, a couplingstructure is provided to couple the far field antenna 302 and the nearfield only RFID tag 200 to the item in close proximity to ensuremagnetic coupling therebetween (or capacitive coupling in the case ofthe near field only RFID tag 205). The portion 702 is selected to have athickness to allow the close coupling, e.g., less than about ¼ inch,less than about ⅛ inch, or less than about 1/16 inch. Again, in someembodiments, the far field antenna 302 and the near field only RFID tag200 are electrically and magnetically coupled. In alternativeembodiments, the coupling structure provides an air gap separationbetween the far field antenna 302 and the near field only RFID tag 200.In the illustrated embodiment, the coupler 506 is removable from theexterior surface 704 to allow the near field only RFID tag 200 to belater removed depending on the use of the RFID tag. For example, a usercould pull on the tab 514 to remove the coupler 506 and the near fieldonly RFID tag 200. Removal of the coupler 506 and near field RFID tag200 results in the far field antenna being magnetically decoupled fromthe near field only RFID tag such that the far field RFID tagging of theitem is now disabled. That is, the proximity relationship (whetherelectrical, magnetic and/or capacitive depending on the tag) between thefar field antenna and the near field only RFID tag is removed. It isnoted that the same or a different near field only RFID tag and coupler506 could be positioned in place on the exterior surface 704 (i.e., theproximity relationship is re-established) and then the item would betagged with a tag operational and readable in both the near field andthe far field. It is noted that the coupler 506 may not be present insome embodiments, and that the near field only RFID tag is attached withadhesive or other coupling structure to the exterior surface 704. Inanother alternative, the coupler 506 may simply take the form of anouter packaging wrap, such as a plastic wrap having the near field onlyRFID tag attached thereto, but removable when the plastic wrap isremoved.

Referring next to FIG. 8, a cross sectional view is shown of anotherimplementation of a decoupled near field only RFID tag 200 and far fieldantenna 302 as affixed to a portion 802 of an item in accordance withone embodiment. In another embodiment, near field only RFID tag 205, 450or other near field only RFID tag could be used. The portion 802 of theitem may be a portion of the item itself or the packaging of the item.In the illustration, the far field antenna 302 is coupled to an exteriorsurface 804 of the portion 802, e.g., it is adhered, printed, orotherwise attached. The near field only RFID tag 200 is illustrated asbeing coupled in proximity to the far field antenna 302 via coupler 806,which at least forms an electrical insulator or barrier between the farfield antenna 302 and the near field only RFID tag 200 to preventelectrical contact. In the illustrated embodiment, the coupler 806completely surrounds the near field only RFID tag 200. In an alternativeembodiment, a sticker completely covers the far field antenna 302 andthe near field only RFID tag 200. For example, the far field antenna andthe near field only RFID tag are formed or positioned on the under sideof a sticker. Thus, in some embodiments, a coupling structure (surface804 and coupler 806) is provided to couple the far field antenna 302 andthe near field only RFID tag 200 to the item in close proximity toensure magnetic coupling therebetween (or capacitive coupling in thecase of the near field only RFID tag 205). In preferred form, theportion of the coupler 806 that separates the far field antenna from thenear field only RFID tag is selected to have a thickness sufficient toallow the close coupling, e.g., less than about ¼ inch, less than about⅛ inch, or less than about 1/16 inch. Again, in some embodiments, thefar field antenna 302 and the near field only RFID tag 200 areelectrically and magnetically coupled, whereas in other embodiments theyare capacitively coupled together. In one alternative, such asillustrated in FIG. 9, an air gap 902 is maintained between the nearfield only RFID tag 200 and the far field antenna 302 to preventelectrical coupling rather than using an insulating or electricallynon-conducting material, such as coupler 806. In the illustratedembodiment, the coupler 806 is adapted to be removable from the exteriorsurface of the far field antenna 302 depending on the use of the RFIDtag. For example, a user could pull on the tab 514 to remove the coupler806 and the near field only RFID tag 200. Removal of the coupler 806 andnear field only RFID tag 200 results in the far field antenna beingmagnetically decoupled from the near field RFID tag such that the farfield RFID tagging of the item is now disabled. That is, the proximityrelationship (whether electrical, magnetic and/or capacitive dependingon the tag) between the far field antenna and the near field only RFIDtag is removed. It is noted that the same or a different near field onlyRFID tag and coupler 806 could be positioned in place on the exteriorsurface 804 (i.e., the proximity relationship is re-established) andthen the item would be tagged with a tag operational and readable inboth the near field and the far field. In an alternative, the coupler806 may simply take the form of an outer packaging wrap, such as aplastic or paper wrap having the near field only RFID tag attachedthereto, but removable when the wrap is removed.

Referring next to FIG. 14, a cross sectional view is shown of anotherimplementation of a decoupled near field only RFID tag 200 and far fieldantenna 302 as affixed to portion 802 of an item in accordance with oneembodiment. This embodiment is similar to the embodiment of FIG. 8 andits variations, except that the coupler 1406 allows for the near fieldonly RFID tag 200 to electrically contact the far field antenna 302.Thus, the far field antenna 302 is electrically and magnetically coupledto the near field only RFID tag. In other words, the far field antenna302 is coupled in proximity to the near field only RFID tag. Similar tocoupler 806, coupler 1406 is adapted to be removable from the exteriorsurface of the far field antenna 302. For example, a user could pull onthe tab 514 to remove the coupler 1406 and the near field only RFID tag200. Removal of the coupler 1406 and near field only RFID tag 200results in the far field antenna being electrically and magneticallydecoupled from the near field only RFID tag such that the far field RFIDtagging of the item is now disabled. That is, the proximity relationship(electrical and magnetic) between the far field antenna and the nearfield only RFID tag 200 is removed. It is noted that the same or adifferent near field only RFID tag and coupler 1406 could be positionedin place on the exterior surface 804 (i.e., the proximity relationshipis re-established) and then the item would be tagged with a tagoperational and readable in both the near field and the far field. In analternative, the coupler 1406 may simply take the form of an outerpackaging wrap, such as a plastic or paper wrap having the near fieldonly RFID tag attached thereto, but removable when the wrap is removed.

Accordingly, several examples are provided for various couplingconfigurations to locate the near field only RFID tag and the far fieldantenna such that they are coupled in proximity, or have a proximityrelationship therebetween. For example, one some cases, the near fieldonly RFID tag and the far field antenna are coupled in proximity toensure magnetic coupling but not electrical contact. In otherembodiments, the various coupling configurations can locate the farfield antenna such that it is in electrical connection with one or moreof the near field only RFID tag, the loop and the integrated circuit ofthe near field only RFID tag so that the near field only RFID tag iselectrically and magnetically coupled to the far field antenna. In otherembodiments, the various coupling configurations can locate the farfield antenna such that it is capacitively coupled with the near fieldonly RFID tag. Examples of coupling structures include, but are notlimited to, removable materials, stickers, labels, portions of the itemor its packaging, other holding structures to hold the near field onlyRFID tag and the far field antenna in a fixed arrangement but with anair gap or insulator separation therebetween or electrical connectiontherebetween, to name a few. Furthermore, the coupling structures mayinclude more than one physical component. Coupling structures may alsobe insulating or non-electrically conducting materials. Additionally,the coupling structures may be configured such that one or both of thenear field RFID tag and the far field antenna can be removed from closeproximity or electrical connection to the each other, i.e., theproximity relationship is removed. This is in contrast to knowintegrated RFID tags where the near field tag and the far field antennaare non-separably integrated into a single integrated unit.

Referring next to FIG. 10, an illustration is shown of a portion of anitem packaging in which a far field antenna 302 is formed on a surfaceof the item packaging and separate from the manufacturing of the nearfield only RFID tag (such as tags 200, 205 or 450) in accordance withone embodiment. In this embodiment, one surface (e.g., an inner surface)of the item to be tagged has a thin metal layer 1002 or film (such asmay be found in the material forming a bag of potato chips). The metallayer 1002 is deposited or printed on the plastic sheet of the item. Inaccordance with one embodiment, the far field antenna 302 is etched orprinted into the metal layer. In a further embodiment, the thin metallayer 1002 may be printed as a conductive printable ink or foil stamp.For example, as illustrated, the metal layer 1002 is applied everywhereexcept about a periphery 1004 to form the far field antenna 302. Theresult is that the elongated conductive strip formed within theperiphery 1004 is used as the far field antenna. Prior testing indicatesthe proper dimensions of the far field antenna in order that it be tunedto the item being tagged (if additional dielectric tuning is needed) sothat the RFID tag will work properly. At this point, a pre-manufacturednear field only RFID tag can be located on the opposite or exterior sideof the item in a location at a central portion of the far field antenna302 and to ensure proximity coupling (electrical and/or magnetic orcapacitor coupling). In other cases, the near field only RFID tag can belocated on top of the far field antenna 302 at a central portion toensure proximity coupling, e.g., using a coupling structure such as asticker, adhesive, etc. In this way, the far field antenna and the nearfield only RFID tag function in both the near field and the far field.

Referring next to FIG. 15, an illustration is shown of a portion of anitem packaging in which the far field antenna 302 is formed on a surfaceof the item packaging in accordance with a variation of the embodimentof FIG. 10. This embodiment is similar to FIG. 10 except that the farfield antenna 302 is formed with the thin metal layer surrounding theperiphery 1004. Electrons are caused to move about the periphery 1004which causes a difference in potential voltage across between the twoelongated lengths of the periphery 1004. This is used to cause currentto occur in the loop of a near field only RFID tag. A pre-manufacturednear field only RFID tag can be removably or non-removably coupled inproximity (electrical and/or magnetic or capacitor coupling) to the farfield antenna 302. In this way, the far field antenna and the near fieldonly RFID tag function in both the near field and the far field. Theembodiment of FIG. 16 illustrates the proximity coupling of the nearfield only RFID tag 205 ensuring a capacitive coupling between the tag205 and the far field antenna.

It is noted that FIGS. 5-10 and 14-16 illustrate several differentfeatures of several embodiments, and that it is understood that whilenot all combinations of features are described, one of skill in the artcan incorporate or combine one or more features from one of more of theembodiments of FIGS. 5-10 and 14-16 to create a device in accordancewith one or more embodiments of the invention.

Many of the embodiments described herein provide the decoupling of themanufacturing of the near field only RFID tag and the far field antennain an RFID device. In many cases, this results in a dramatic reductionin costs a supplier must bear to ensure item level tagging while meetingtag certifications. For example, by using a design in which all tags canuse the same basic near field only RFID tag, such near field only RFIDtags 200 and 205, regardless of the item being tagged, the supplier canachieve great economies of scale since such pre-manufactured near fieldtags can be ordered in bulk. Furthermore, the supplier will have lowercosts in designing the far field antennas in many cases if simpleconductive wiring is used or if integrated with label or packagingdesign. Accordingly, it is believed that this reduction is cost shouldmake it much more cost effective and feasible to implement item leveltagging.

Next, referring to FIGS. 11-13, illustrations are shown of example itemsto incorporate RFID tagging devices wherein the far field antenna designis incorporated into the product label design in accordance with severalembodiments. In the illustration of FIG. 11, the material used to makethe labeling of the package includes a metallic component which may beused to incorporate the far field antenna. For example, the label inthis case includes a metal or conductive material. Alternatively, thelabel could include a printable conductive ink or a foil stamp or otherthin metallic or conductive layer. Locations 1102 and 1104 provideexample locations where a far field antenna may be implemented. Bothlocations 1102 and 1104 are generally linear and suitable to form thefar field antenna. It is understood that the far field antenna is notrequired to be a straight linear structure in all embodiments, but isshown so here for simplicity. That is, it is understood that the farfield antenna may be implemented in other non-linear arrangements orlinear arrangements that change directions or bend around aspects of thelabel. Should location 1102 or 1104 be implemented as a far fieldantenna, the near field only RFID tag could be located on top of acentral portion of the location or underneath a central portion of thelocation to provide magnetic coupling. Alternatively, the near fieldonly RFID tag could be located on top of an end portion of the locationor underneath an end portion of the location to provide efficientcapacitive coupling. In FIG. 12, location 1202 is the left vertical edgeof the Nutritional Facts product label printed on the item, which is aplastic bottle. The edge of the Nutritional Facts label could be printedwith a conductive ink or a foil stamp at location 1202 (or about itsentire periphery) and the near field only RFID tag could be located ontop of the location 1202 or underneath it (inside the bottle) using asticker or other adhesive material, for example. In a further example,FIG. 13 illustrates a cardboard box package and includes example linearlocations 1302, 1304 and 1306 as possible locations to implement a farfield antenna in the labeling of the item. Again, the far field antennamay be printed with conductive ink or have a foil stamp applied theretoduring design and manufacture of the labeling/cardboard box. Theselocations are certainly not the only locations to implement a far fieldantenna, and are provided by way of example. This is important for someembodiments in that it allows the item manufacturer to design the farfield antenna together with the product or label design (such asdescribed in some embodiments of FIG. 4C) and allow use of standard, lowcost pre-manufactured near field only RFID tags. This provides addedflexibility and new efficiencies for suppliers to provide cost effectiveitem level tagging.

Referring next to FIG. 17, a flowchart of the steps performed in one ormore manufacturing methods in accordance with several embodiments.Embodiments of the methods of FIG. 17 may be used to manufacture one ormore of the RFID tag devices and other RFID tag devices as describedherein.

Initially, a near field only RFID tag that does not function as a farfield tag is obtained (Step 1702). In some embodiments, the near fieldonly RFID 200, 205 and/or 450 may be used. In several embodiments, thenear field only RFID tag includes an integrated circuit or chip and anear field loop, but does not include a tag antenna or far fieldantenna. In one embodiment, the near field only RFID tag is obtained byremoving the far field antenna from a commercially available integratednear and far field RFID tag. In another embodiment, such as described inFIG. 4E, for example, the near field only RFID tag is manufactured inmass by an RFID tag manufacturer. In some embodiments, the near fieldonly RFID tag is not designed to account for the dielectric propertiesof any particular item to be tagged.

Next, a conductive element is tuned to an item to be tagged, where theconductive element is adapted to function as a far field antenna (Step1704). In some embodiments, this is done in a separate manufacturingprocess, for example, by an item or packaging manufacturer or packager,such as described in connection with FIG. 4E. This tuning accounts forthe particular dielectric properties of the item to be tagged, orproduct attached to the item (product label) actually tagged. Whenreferring to the tuning of the conductive element, generally, onepurpose of the RFID tag device is to provide an impedance matchingstructure to couple electromagnetic energy (e.g., radio frequency) infree space to an integrated circuit containing the integrated circuit orchip. The dielectric properties of the item to be tagged can alter theimpedance match of the RFID tag device such that the conductive element(e.g., far field antenna) may become de-tuned. This can result in readerrors. Thus, tuning can be referred to as impedance matching. An effectof being substantially tuned is that the RFID device will performsubstantially efficiently as a far field device. By designing theconductive element (for example, designing its dimensions), theconductive element can be tuned to a particular item. In someembodiments, this tuning is done by trimming the length of theconductive element while being influenced by the dielectric of thetarget item (or otherwise printing various dimensioned conductiveelements) until an optimal impedance match is found. In one embodiment,through testing, different dimensions of the conductive element are usedand an optimal tuned dimension results when the performance of the RFIDtag sensitivity and backscatter strength on either side of the dimensiondrops. In several embodiments, advantageously, the near field only RFIDtag is not required to be tuned and thus, can be cost effectively massproduced, whereas the conductive element is tuned to the item in aseparate manufacturing process. In some embodiments, this step isoptional if tuning is not required for a particular item to be tagged.

Next, the near field only RFID tag and the conductive element arecoupled to the item such that the near field only RFID tag and theconductive element are coupled in proximity to each other so that theRFID tag will function in both the near field and far field (Step 1706).This may be done in any variety of ways and implemented by a variety ofcoupling structures, couplers and/or surfaces, such as described andillustrated herein. For example, in one embodiment, the conductiveelement is formed from a printable conductive ink that is printed to asurface of the item (or its packaging). In another embodiment, theconductive element is formed or applied using a foil stamp to a surfaceof the item (or its packaging). Additionally, in one embodiment, theconductive element is located relative to the near field RFID tag suchthat the conductive element is magnetically coupled to the near fieldonly RFID tag. In another embodiment, the conductive element is locatedrelative to the near field RFID tag such that the conductive element iscapacitively coupled to the near field only RFID tag. In a furtherembodiment, the conductive element is located relative to the near fieldRFID tag such that the conductive element is electrically contacting thenear field only RFID tag.

Next, in accordance with some embodiments, one of the near field onlyRFID tag and the conductive element are decoupled from the item, thenear field only RFID tag and the conductive element no longer coupled inproximity to each other such that the RFID tag no longer functions or isreadable in the far field (Step 1708). In some embodiments, this isillustrated in simplified form in FIGS. 3B and 3E. This may be done inany variety of ways and implemented by a variety of coupling structures,couplers and/or surfaces, such as described and illustrated herein.

Next, in accordance with some embodiments, the one of the near fieldonly RFID tag and the conductive element (or a replacement or differentone of the near field only RFID tag and the conductive element) isrecoupled to the item, the near field only RFID tag and the conductiveelement again coupled in proximity to each other such that the RFID tagagain functions in both the near field and the far field (Step 1710). Insome embodiments, this is illustrated in simplified form in FIGS. 3C and3F. This may be done in any variety of ways and implemented by a varietyof coupling structures, couplers and/or surfaces, such as described andillustrated herein.

Accordingly, as exemplified by the examples described herein, severalradio frequency identification (RFID) devices are provided. In oneembodiment, a radio frequency identification (RFID) device comprises anitem having a first location and a second location, and one of a nearfield only RFID tag and a conductive element coupled to the firstlocation of the item, wherein the near field only RFID tag does notfunction as a far field RFID tag, wherein the conductive element isadapted to function as a far field antenna. The second location of theitem is adapted to receive and allow to be coupled thereto the other ofthe near field only RFID tag and the conductive element, the secondlocation located relative to the first location such that when the otherof the near field only RFID tag and the conductive element is coupledthereto, the conductive element will be coupled in proximity to the nearfield only RFID tag such that the RFID device will function in both anear field and a far field.

Additionally, various methods are provided to make a radio frequencyidentification (RFID) device. In one embodiment, a method of making aradio frequency identification (RFID) device comprises the steps:coupling a pre-manufactured near field only RFID tag to an item, whereinthe near field only RFID tag does not function as a far field RFID tag;and coupling a conductive element to the item, wherein the conductiveelement is adapted to function as a far field antenna; wherein thecoupling steps result in that the near field only RFID tag is located ina proximity relationship to the conductive element such that the RFIDdevice functions in both a near field and a far field; and wherein oneof the coupling steps comprises removably coupling a respective one ofthe near field only RFID tag and the conductive element to the item suchthat the proximity relationship between the near field only RFID tag andthe conductive element may be later removed such that the RFID device nolonger functions in the far field.

In another embodiment, a method of making a radio frequencyidentification (RFID) device comprises the steps: coupling, in a firstmanufacturing process, one of a pre-manufactured near field only RFIDtag and a conductive element to an item, wherein the near field onlyRFID tag does not function as a far field RFID tag, wherein theconductive element is adapted to function as a far field antenna; andcoupling, in a second manufacturing process separate from the firstmanufacturing process, the other of the near field only RFID tag and theconductive element to the item, wherein the coupling steps result inthat the near field only RFID tag is located proximate to and coupled inproximity to the conductive element such that the RFID device functionsin both a near field and a far field.

The following portion of the specification and supporting figuresdescribes RFID sensors, systems and methods in which RFID devices withdecoupled near field only RFID tags and far field antennas are used toimplement RFID sensors in accordance with some embodiments. Referringfirst to FIGS. 18-20, illustrations are shown of an RFID sensor systemincluding an RFID device 1801 having a decoupled near field only RFIDtag and far field antenna architecture such as described above and usedin a manner to implement an RFID sensor in accordance with someembodiments. The sensor system 1800 includes a near field only RFID tag1802, a far field antenna 1804 (which may be generically referred to asa conductive element, which is understood to be electricallyconducting), an RFID reader 1808 having a reader antenna 1806 andcoupled to a controller 1810. Also shown are interrogation signals 1820,return signals 1822 (also referred to as reflected signals orbackscattered signals), a near field 1812 and a far field 1814. It isnoted that the near field only RFID tag is intended to not function inand of itself as a far field RFID device.

The near field only RFID tag 1802 and the far field antenna 1804 areconfigured to be selectively movable between at least a first positionand a second position, where in a first position (e.g., illustrated inFIG. 18 and FIG. 20), the near field only RFID tag and the far fieldantenna are located relative to each other such that the far fieldantenna is substantially decoupled from the near field only RFID tag.When so decoupled, the RFID device 1801 only operates in the near field1812 with respect to the RFID reader 1808. In this decoupled position,since the near field only RFID tag is not coupled to the far fieldantenna, the near field only RFID tag does not backscatter theinterrogation signals 1820 from the reader 1808 which is in the farfield 1814. Thus, the RFID device 1801 is not readable by the RFIDreader 1808, as illustrated in FIGS. 18 and 20.

When the near field only RFID tag 1802 and the far field antenna 1804are located in the second position relative to each other (e.g.,illustrated in FIG. 19), the far field antenna is substantially coupledto the near field only RFID tag. When so coupled, the RFID device 1801operates in both the near field 1812 and the far field 1814 with respectto the RFID reader 1808. In this coupled position, since the near fieldonly RFID tag is coupled to the far field antenna, the near field onlyRFID tag does receive the interrogation signals 1820 and sends orbackscatters the return signals 1822 to the antenna 1806 of the reader1808 which is in the far field 1814. Thus, the RFID device 1801 is nowreadable by the RFID reader 1808, as illustrated in FIG. 19.

By selectively moving one or both of the near field only RFID tag 1802and the far field antenna 1804 relative to each other between coupledand decoupled positions, one can control whether or not the RFID device1801 can be read by the RFID reader 1808 in the far field 1814. In asensor system in accordance with some embodiments, one or more of thereading of the RFID device 1801, the non-reading of the RFID device1801, or the transition between reading and non-reading of the RFIDdevice 1801 by the RFID reader 1808 may be interpreted or correlated bythe controller 1810 as a state of the RFID device and/or an occurrenceof an event. For example, in some embodiments, the controller correlatesthe fact that the RFID device 1801 can be read by the reader 1808 (i.e.,the RFID device is visible to the reader) to a first state of the RFIDdevice, and correlates the fact that the RFID device 1801 is not read bythe reader 1808 (i.e., the RFID device is not visible to the reader) toa second state of the RFID device. In some embodiments, one or both ofthese states may be correlated by the controller 1810 to the occurrenceof first or second events. In some embodiments, the controller 1810 cancorrelate the point in time when the reading of the RFID device 1801changes (e.g., becomes readable or becomes unreadable by the reader)with a transition or trigger signaling an occurrence of an event. Forexample, the controller may detect a transition between movement betweenthe first and second positions by repetitively attempting to read theRFID device 1801. If the RFID device 1801 is repetitively not read, thenit is read, the controller 1810 detects that the near field only RFIDtag and the far field antenna are now sufficiently coupled so that theRFID device 1801 now functions in the far field. On the other hand, ifthe RFID device 1801 is repetitively being read, then it is not (i.e.,it disappears from the reader perspective), the controller 1810 detectsthat the near field only RFID tag and the far field antenna are nowsufficiently decoupled so that the RFID device 1801 no longer functionsin the far field.

It is understood that the near field only RFID tag 1802 stores data, atleast a portion of which is modulated onto the reflected signals 1822.When the near field only RFID tag and far field antenna are located tobe sufficiently coupled, the reader antenna 1806 receives the reflectedsignals 1822 and the reader 1808 extracts the modulated data which isforwarded to the controller 1810. In some embodiments, the controller1810 processes the received data as is known in the art. For example, insome embodiments, at least a portion of the data corresponds to an ID ofthe RFID device 1801, which is matched by the controller to known IDs inorder to determine which RFID device it is reading and/or what type ofsensor is being implemented. In some embodiments of a sensor system, thecontroller is programmed to correlate the reading of RFID devices 1801with known IDs to certain events or occurrences. Depending on the event,based on the reading of a given RFID device, the controller 1810 mayoutput signaling to other system components or to an operator. In someexamples, the reading of an given RFID device 1801 in which the nearfield only RFID tag and the far field antenna are sufficiently coupledto be read in the far field 1814 may be interpreted by the controller asvarious states and/or events. Some example events and/or states in anexemplary application of a retail store may include: sensing the openingand/or closing of a door or lid, a trigger for customer assistance, atrigger that replenishment of goods is needed, a trigger than a givenRFID device is within range of the reader, a stock location tool, toname a few.

It is noted that in some embodiments, the reader antenna 1806 is locatedoutside of the near field 1812 but within the far field 1814. It is alsonoted that the reader 1808 and/or controller 1810 may be located withinor outside of the far field 1814 as long as the reader antenna 1806 iswithin the far field 1814.

Referring next to FIG. 21, shown is an illustration of the RFID sensorsystem 1800 of FIG. 18 in which the reader antenna 1806 is within thenear field 1812 in accordance with some embodiments. In theseembodiments, regardless of whether the near field only RFID tag and thefar field antenna of the RFID device 1801 are in the coupled position orin the decoupled position, the RFID device 1801 can be read by thereader 1808. In some embodiments, in this configuration, the controller1810 can be configured to cause the reader 1808 to transmit signaling tothe near field only RFID tag 1802 that causes the near field only RFIDtag to change at least a portion of its data stored in the near fieldonly RFID tag. This effectively re-programs the near field only RFID tag1802. Again, is also noted that the reader 1808 and/or controller 1810may be located within or outside of the near field 1812 as long as thereader antenna 1806 is within the near field 1812.

Additionally, the data or ID stored in the near field only RFID tag 1802may be re-programmed by the controller 1810 when the reader antenna 1806is in the far field, but only when the near field only RFID tag and thefar field antenna are located relative to each other to be sufficientlycoupled, such as shown in FIG. 19.

It is noted that the RFID device 1801 is illustrated to be similar tothe near field only RFID tag 1802 and far field antenna 1804 of FIGS.3D-3F in that they are configured to be capacitively coupled together.It is understood that the RFID device may be electrically and/ormagnetically coupled, such as the magnetically coupled near field onlyRFID tag and far field antenna of FIGS. 3A-3C. The near field only RFIDtag and the far field antenna may be any of those described herein andother variations.

It is also noted that although the illustrations of FIGS. 18-21 show thenear field only RFID tag moving relative to a stationary far fieldantenna, other configurations are possible. For example, the far fieldantenna can be movable relative to a stationary near field only RFIDtag, or both the near field only RFID tag and far field antenna moverelative to each other to be coupled or not coupled.

In some embodiments, since the near field only RFID tag 1802 may beembodied as a passive device (i.e., no battery power is required),inexpensive RFID-based sensors may be implemented in locations whenpower is not available. In such cases, RFID-based sensors may be easilyimplemented in any location by locating the RFID device having thedecoupled architecture in a location where it may only be read in thefar field. Thus, RFID readers may be positioned at locations where poweris available and that are near the locations of devices/movements thatare to be sensed. In a large retail environment where merchandise andfixturing frequently move, simple to set up and easily relocatableRFID-based sensors may be implemented using RFID devices that may bemoved together with fixed readers. Known user activated switches, callbuttons, etc. are often required to be installed at locations wherepower is available (or alternatively, battery power is required) andsuch devices can be relatively expensive. It is well known than thebasic components of RFID devices readable in the far field by RFIDreaders are low cost. In particular applications where RFID readers arealready implemented for use, RFID based devices may be easily added tocreate RFID-based sensors.

Furthermore, in some embodiments, the movement of the near field onlyRFID tag 1802 and the far field antenna 1804 relative to each otheroccurs through mechanical, physical movement of one or both of the nearfield only RFID tag and the far field antenna. This movement may be theresult of human, physical intervention. For example, a person may pressa button, open a door, or otherwise bring to components into proximity,e.g., by sliding, shifting, lifting, pivoting, rotating one or bothcomponents. The movement may also be a result of animal or other livingbeing triggering physical movement, such as an animal that pushes a doorcontaining one of the near field only RFID tag and the far field antennaagainst or a door frame or other component having the other of the nearfield only RFID tag and the far field antenna. The movement may also bethe result of other physical movement triggers. For example, as itemsare removed from an area by human or machine, components including thenear field only RFID tag and far field antenna are brought into aproximity relationship such that they are coupled together to functionas a far field RFID device. Additionally, the relative movement of thenear field only RFID tag and the far field antenna may be triggered inother ways. For example, in one embodiment, mechanical pressure from aspring loaded member causes a far field antenna and a near field onlyRFID tag to be brought into proximity as weight is removed from themember or objects resisting spring extension are removed.

Referring next to FIGS. 22-27, various coupling structures to allow forthe relative movement of the near field only RFID tag 1802 and the farfield antenna 1804 so that the can be selectively coupled and decoupledare described. In FIGS. 22-24, exemplary coupling structures are shownin which the coupling structure is integrated, for example, in a housingor integrated device.

In FIG. 22, the RFID device 2200 includes coupling structure 2202 whichcontains the near field only RFID tag 1802 and the far field antenna1804. The far field antenna is permanently or removably fixed to a firstportion 2204 of the coupling structure 2202 whereas the near field onlyRFID tag 1802 is permanently or removably fixed to a second portion 2206of the coupling structure 2202. The first portion 2204 is fixed to thecoupling structure (or is integral with the coupling structure) suchthat the far field antenna 1804 does not move. The second portion 2206is configured to be moveable relative to the coupling structure 2202 andthe first portion 2204 to allow the near field only RFID tag to bemovable between at least a decoupled position (at location 2207) and acoupled position (at location 2208) proximate the far field antenna. Theexact configuration of the coupling structure 2202 and the portions 2204and 2206, and the components to effect this configuration will depend onthe application of the RFID device within the RFID sensor system. Forexample, in the event the RFID device is implemented as a push button,in some embodiments, the second portion 2206 may be part of the buttonstructure that is movable within a button housing. Many otherconfigurations are possible.

In the embodiments of the RFID device 2300 of FIG. 23, the secondportion 2206 of the coupling structure 2202 is fixed to the couplingstructure (or is integral with the coupling structure) such that thenear field only RFID tag 1802 does not move. The first portion 2204 isconfigured to be moveable relative to the coupling structure 2202 andthe second portion 2206 to allow the far field antenna to be movablebetween at least a decoupled position (at location 2209) and a coupledposition (at location 2208) proximate the near field only RFID tag.Again, the exact configuration of the coupling structure 2202 and theportions 2204 and 2206 will depend on the application of the RFID devicewithin the RFID sensor system.

In the embodiments of the RFID device 2400 of FIG. 24, both the firstportion 2204 and the second portion 2206 are configured to be moveablerelative to the coupling structure 2202 to allow both the near fieldonly RFID tag and the far field antenna to be movable between at least adecoupled position (at locations 2207 and 2209) and a coupled position(at locations 2402 and 2404). The exact configuration of the couplingstructure 2202 and the portions 2204 and 2206 will depend on theapplication of the RFID device within the RFID sensor system.

It is noted that in some embodiment, when referring to portions of thecoupling structure that are integrated, such portions may or may not becontained within or integrated into one housing or assembly and areoften directly mechanically fixed together. In some embodiments, thefirst portion and the second portion are integrated into a singlestructure.

In FIG. 25, the RFID device 2500 includes a non-integrated couplingstructure to selectively couple and decouple the near field only RFIDtag 1802 and the far field antenna. The near field only RFID tag 1802 ispermanently or removably fixed to a first portion 2504 of the couplingstructure whereas the far field antenna 1804 is permanently or removablyfixed to a second portion 2504 of the coupling structure. In thisembodiment, the second portion 2504 is positionally fixed such that thefar field antenna 1804 does not move. The first portion 2502 isconfigured to be moveable relative to the second portion 2504 to allowthe near field only RFID tag to be selectively movable between at leasta decoupled position (at location 2505) and a coupled position (atlocation 2506) proximate the far field antenna. The exact configurationof the first portion 2502 and the second portion 2504, and thecomponents to effect this configuration will depend on the applicationof the RFID device within the RFID sensor system. For example, in theevent the RFID device is implemented as a door open/close sensor, insome embodiments, the first portion 2502 may be part of the movable doorwhereas the second portion 2504 may be a part of a fixed separate doorframe, door stop or door post, for example. Many other configurationsare possible.

In the embodiments of the RFID device 2600 of FIG. 26, the first portion2502 is positionally fixed such that the near field only RFID tag 1802does not move. The second portion 2504 is configured to be moveablerelative to the first portion 2502 to allow the far field antenna to beselectively movable between at least a decoupled position (at location2507) and a coupled position (at location 2506) proximate the near fieldonly RFID tag. The exact configuration of the first portion 2502 and thesecond portion 2504, and the components to effect this configurationwill depend on the application of the RFID device within the RFID sensorsystem.

In the embodiments of the RFID device 2700 of FIG. 27, both the firstportion 2502 and the second portion 2504 are configured to be moveablerelative to each other to allow both the near field only RFID tag andthe far field antenna to be selectively movable between at least adecoupled position (at locations 2505 and 2507) and a coupled position(at locations 2702 and 2704). The exact configuration of the firstportion 2502 and the second portion 2504, and the components to effectthis configuration will depend on the application of the RFID devicewithin the RFID sensor system.

It is noted that in some embodiment, when referring to portions of thecoupling structure that are non-integrated, such portions are often notdirectly mechanically fixed together even though they may be indirectlycoupled together by an overall frame or assembly. In some embodiments,the first portion and the second portion are separate physicalstructures.

It is also noted that when generally referring to portions of couplingstructure that are configured to allow one or both of the near fieldonly RFID tag and far field antenna to be moved relative to each other,such movement may be provided by any known physical structures thatallow for one or both portions to be depressed, slid, shifted, lifted,pivoted, rotated, peeled and re-adhered, etc. relative to each other forexample.

Referring next to FIG. 28, shown is an illustration of an RFID device2800 in which the far field antenna 1804 may be selectively moved intoposition to couple with one of two near field only RFID tags 1802A and1802B for use in an RFID sensor system in accordance with someembodiments. That is, in some embodiments, the RFID device 2800 includesmore than one near field only RFID tag. The far field antenna may beswitched or selectively moved so that in one position (at location2803), the far field antenna is sufficiently coupled to the near fieldonly RFID tag 1802A so that the near field only RFID tag 1802A and thefar field antenna 1804 together operate in both the near field and thefar field with respect to the RFID reader. In the position of location2803, the far field antenna 1804 is decoupled from the near field onlyRFID tag 1802B such that the near field only RFID tag 1802 is onlyreadable by a reader having an antenna in the near field. That is, areader having an antenna located in the far field can read near fieldonly RFID tag 1802A, but not the near field only RFID tag 1802B.

When the far field antenna 1804 is selectively moved from location 2803to a second position (at location 2802), the far field antenna 1804 isnow coupled to near field only RFID tag 1802B and decoupled with nearfield only RFID tag 1802A. Thus, a reader having an antenna located inthe far field can now read near field only RFID tag 1802B, but not thenear field only RFID tag 1802A. In some applications, it may bedesirable to be able to alternatively read two different known nearfield only RFID tags. For example, in a simple swinging doorapplication, the far field antenna 1804 may be fixed to the swingingdoor, where near field only RFID tag 1802A is fixed to a stationaryframe on one side of the door and near field only RFID tag 1802B isfixed to a stationary frame on another side of the door. Depending onwhich near field only RFID tag is read by the reader will indicate theposition of the swinging door. In another example, a push button devicemay be configured such that the far field antenna 1804 is coupled withnear field only RFID tag 1802A when un-pressed, and when pressed, thefar field antenna 1804 is moved to be coupled with near field only RFIDtag 1802B and no longer be coupled with near field only RFID tag 1802A.Depending on which tag is read, the controller coupled to the reader candetermine the switch or button position.

It is noted that for simplicity, the coupling structures are not shownin FIG. 28 (and in FIGS. 29-34), but it is understood that any of thecoupling structures and their variations as described herein andotherwise known may be used. It is also understood that the couplingstructure may be integrated or non-integrated, such as described herein.

Referring next to FIG. 29, shown is an illustration of an RFID device2900 in which the near field only RFID tag 1802 may be selectively movedinto position to couple with one of two far field antennas 1804A and1804B for use in an RFID sensor system in accordance with someembodiments. This embodiment is similar to that described in FIG. 28;however, a single near field only RFID tag 1802 is selectively coupledwith one far field antenna then to another. There may be manyapplications where such architecture is implemented. For example, insome embodiments, the far field antennas 1804A and 1804B may bedifferent types of antennas (e.g., having different polarizationcharacteristics and/or are tuned differently) that can be differentiatedby the reader, or read by different readers.

Referring next to FIG. 30, shown is an illustration of an RFID device3000 in which the far field antenna 1804 may be selectively moved intoposition to couple with none or one of two near field only RFID tags1802A and 1802B for use in an RFID sensor system in accordance with someembodiments. This embodiment is similar to that of FIG. 28; however, thedevice 3000 illustrates that in addition to being located at positionsthat will couple the far field antenna 1804 to the near field tags 1802Aand 1802B (locations 2802 and 3002), the far field antenna 1804 may beselectively movable to other locations (e.g., location 3004) in whichthe far field antenna is decoupled from all near field tags of the RFIDdevice 3000.

Furthermore, referring to FIG. 31, an RFID device 3100 is shown in whichthe far field antenna 1804 may be selectively moved into position tocouple with none or any one of a plurality of near field only RFID tagsfor use in an RFID sensor system in accordance with some embodiments.Thus, in this embodiment, the RFID based sensor includes an RFID devicethat has a 1:N far field antenna to near field only RFID tag couplingrelationship. In the illustrated embodiment, there are three near fieldtags 1802A, 1802B and 1802C. As illustrated, the far field antenna 1804may be selectively moved into at least different positions 3102A-D. Inposition 3102D, the far field antenna is decoupled with all near fieldonly RFID tags. In position 3102A, the far field antenna is only coupledto near field only RFID tag 1802A such that only near field only RFIDtag 1802A can be read by a reader having an antenna in the far field. Inposition 3102B, the far field antenna is only coupled to near field onlyRFID tag 1802B such that only near field only RFID tag 1802B can be readby a reader having an antenna in the far field. And, in position 3102C,the far field antenna is only coupled to near field only RFID tag 1802Csuch that only near field only RFID tag 1802C can be read by a readerhaving an antenna in the far field. It is understood that one or more ofthe near field tags 1802A-C may be configured to move relative to thefar field antenna 1804. It is also understood that there may be otherdecoupled locations not illustrated, e.g., between locations 3102A and3102B. In one example, a spring-loaded member having a far field antennaof a merchandising display or rack moves to different locations asmerchandise is removed from rack, and as the member moves the far fieldantenna is coupled to different near field only RFID tags in order tosignal different levels of inventory in the rack. In this example, theRFID based sensor system would sense levels of inventory and whenreplenishment is needed.

Referring next to FIG. 32, shown is an illustration of an RFID device3200 in which the near field only RFID tag 1802 may be selectively movedinto position to couple with none or any one of a plurality of far fieldantennas for use in an RFID sensor system in accordance with someembodiments. Thus, in this embodiment, the RFID based sensor includes anRFID device that has a 1:N near field only RFID tag to far field antennacoupling relationship. In the illustrated embodiment, there are threefar field antennas 1804A, 1804B and 1804C. As illustrated, the nearfield only RFID tag 1802 may be selectively moved into at leastdifferent positions 3102A-D. In position 3102D, the near field only RFIDtag is decoupled with all far field antennas. In position 3102A, thenear field only RFID tag is only coupled to far field antenna 1804A suchthat near field only RFID tag 1802 can only be read by a reader incommunication with far field antenna 1804A. In position 3102B, the nearfield only RFID tag is only coupled to far field antenna 1804B such thatnear field only RFID tag 1802 can only be read by a reader incommunication with far field antenna 1804B. And, in position 3102C, thenear field only RFID tag 1802 is only coupled to far field antenna 1804Csuch that near field only RFID tag 1802 can only be read by a reader incommunication with far field antenna 1804C. It is understood that one ormore of the far field antennas 1804A-C may be configured to moverelative to the near field only RFID tag 1802. It is also understoodthat there may be other decoupled locations not illustrated, e.g.,between locations 3102A and 3102B.

It is noted that in some embodiments of the devices 3100 and 3200 ofFIGS. 31 and 32, a coupling structure is provided such that the order ofmovement from the coupling of a given near field only RFID tag to agiven far field antenna and so on may be different than is illustrated.

Referring next to FIG. 33, shown is an illustration of an RFID device3300 in which the far field antenna 1804 may be selectively moved intoposition to couple with two near field only RFID tags 1802A and 1802B atthe same time for use in an RFID sensor system in accordance with someembodiments. Similar to the embodiments of FIGS. 23 and 26, the farfield antenna 1804 is movable; however, it is movable to couple at thesame time to two or more near field tags 1802A and 1802B. In this way,when the far field antenna 1804 is located at position 3304, the farfield antenna 1804 is decoupled from the near field only RFID tags sothat neither may be read by a reader having an antenna in the far field.When the far field antenna 1804 is selectively positioned to location3302, the far field antenna 1804 is coupled to both near field only RFIDtags 1802A and 1802B so that they both may be read by a reader having anantenna in the far field. There may be several applications in which itis desired to have more than one near field only RFID tag readable inthe far field, and at a minimum, may be provided for redundancy in tagreading.

Alternatively, it is understood that the far field antenna 1804 may bepositionally fixed and the two tags 1802A and 1802B are movable, or thatboth the far field antenna 1804 and the tags 1802A and 1802B moverelative to each other.

Referring next to FIG. 34, shown is an illustration of an RFID device3400 in which the near field only RFID tag 1802 may be selectively movedinto position to couple with two far field antennas 1804A and 1804B atthe same time for use in an RFID sensor system in accordance with someembodiments. Similar to the embodiments of FIGS. 22 and 25, the nearfield only RFID tag 1802 is movable; however, it is movable to couple atthe same time to two or more far field antennas 1804A and 1804B. In thisway, when the near field only RFID tag 1802 is located at position 3304,the near field only RFID tag 1802 is decoupled from the far fieldantennas so that the near field only RFID tag 1802 may not be read by areader having an antenna in the far field. When the near field only RFIDtag 1802 is selectively positioned to location 3302, the near field onlyRFID tag 1802 is coupled to both far field antennas 1804A and 1804B sothat the tag 1802 may be read by one or more readers having one or moreantennas in the far field in communication with the far field antennas1804A and 1804B. There may be several applications in which it isdesired to have one near field only RFID tag 1802 readable in the farfield using more than one far field antenna. Alternatively, it isunderstood that the near field only RFID tag 1802 may be positionallyfixed and the two antennas 1804A and 1804B are movable, or that both thenear field only RFID tag 1802 and the antennas 1804A and 1804B moverelative to each other.

It is also noted that while the illustrations of FIGS. 19-34 showdiscrete locational positions in which the near field only RFID tag 1802and far field antenna 1804 are coupled and decoupled, there may be morethan one position in which the near field only RFID tag and the farfield antenna are coupled together. Additionally, in some embodiments,there may more than one position in which the near field only RFID tagand the far field antenna are decoupled. For example, in someembodiments, a coupling structure could be provided that allows multiplediscrete positional locations, one or more of which provide a couplingbetween the near field only RFID tag and the far field antenna, and oneor more of which provide that the near field only RFID tag and the farfield antenna are decoupled. In other embodiments, the couplingstructure is configured such that there may be multiple non-discretedecoupling positions. For example, in a swinging door application, atapproximately certain locational positions, the near field only RFID tagand the far field antenna will be coupled, whereas at multiplelocational positions through the continuous movement of the door whenswinging open or closed, that the near field only RFID tag and the farfield antenna will be decoupled in which case the RFID device can not beread by a reader having an antenna in the far field.

Referring next to FIG. 35, shown is a flowchart illustrating the stepsinvolved methods performed in an RFID sensor system in accordance withsome embodiments. Embodiments of the methods may be performed using anyof the RFID devices described herein having an architecture in which thenear field only RFID tag and the far field antenna may be selectivelycoupled and decoupled. It is understood that the methods of theseembodiments may also be performed by components, systems and variationsnot specifically described herein.

In accordance with some embodiments, a near field only RFID tag and aconductive element of an RFID device are located at one of a firstposition and a second position relative to each other, when in the firstposition the RFID device only operates in a near field with respect toan RFID reader, and when in the second position the RFID device operatesin both the near field and the far field with respect to the RFID reader(Step 3502). This may be done in a variety of ways using a variety ofpossible coupling structures such as described herein. For example, insome embodiments, one or both of the near field only RFID tag and thefar field antenna are movable relative to the other to locate the nearfield only RFID tag and the far field antenna in either the firstposition or the second position. In some embodiments, the locating maybe the result of user mechanical manipulation or other living beingmechanical manipulation of coupling structure fixed to the near fieldonly RFID tag and the far field antenna.

When in the first position, in one embodiment, the near field only RFIDtag and the far field antenna are located relative to each other suchthat the far field antenna is sufficiently decoupled from the near fieldonly RFID tag in order that the RFID device only operates in a nearfield with respect to an RFID reader having an antenna in the far field.When in the second position, in one embodiment, the near field only RFIDtag and the far field antenna are located relative to each other suchthat the far field antenna is sufficiently coupled to the near fieldonly RFID tag such that the RFID device may be read by a reader havingan antenna in the far field.

Next, the near field only RFID tag and the conductive element arelocated at another of the first position and the second positionrelative to each other (Step 3504). In some embodiments, this involvesphysically moving one or both of the near field only RFID tag and thefar field antenna relative to each other such that they are located inthe other of the first position and the second position. Any couplingstructure described herein or otherwise capable of allowing ortriggering this locating step may be used.

Next, the RFID device is read with an RFID reader having an antenna inthe far field with respect to the RFID device and the RFID device is inthe second position (Step 3506). For example, this is done in someembodiments by causing the transmission of interrogation signals fromthe RFID reader which are reflected by the RFID device in the secondposition. The reflected signals are received by the reader antenna andpassed to the RFID reader, which extracts data in the reflected signalsfrom the RFID device. In some embodiments, a control circuit orcontroller coupled to the RFID reader receives this data from the RFIDdevice, matches at least a portion thereof to a known ID stored inmemory of the control circuit to verify that the known RFID device hasnow been read.

Next, the reading of the RFID device is correlated as a first state ofthe RFID device (Step 3508). For example, in some embodiments, this stepcan be performed by the control circuit which has been configured tocorrelate the reading of the RFID device to a predetermined state of theRFID device. In some embodiments, the state of the RFID device mayrepresent that the RFID device is open, closed, activated, off, etc.

Next, the lack of reading the RFID device in the first position with theRFID reader having an antenna in the far field is correlated as a secondstate of the RFID device (Step 3510). For example, in some embodiments,this step can be performed by the control circuit which has beenconfigured to correlate the non-reading of the RFID device to apredetermined state of the RFID device. In some embodiments, the stateof the RFID device may represent that the RFID device is open, closed,activated, off, etc. In some embodiments, the second state is oppositethe first state. It is noted that in some embodiments, Step 3510 isperformed before Steps 3506 and 3508.

Next, and/or after Step 3504, an occurrence of the second locating stepis detected using the RFID reader located in the far field with respectto the RFID device (Step 3512). In some embodiments, this is detected bya changing on the reading status of the RFID device. That is, responsiveto repeated attempts to read the RFID device, it is read, but then thedevice is suddenly no longer read in the far field by the RFID reader,this is interpreted or correlated as a locating of the near field onlyRFID tag and the far field antenna relative to each other from thesecond position to the first position. Furthermore, responsive torepeated attempts to read the RFID device, it is not read, but thensuddenly read in the far field by the RFID reader, this is interpretedor correlated as a locating of the near field only RFID tag and the farfield antenna relative to each other from the first position to thesecond position. Depending on the configuration corresponding to theRFID device being read or not, the locating is correlated to theoccurrence of an event. Examplary events may include the opening of adoor, the closing of a door, the activation is an alarm or use helpbutton, for example.

It is further noted that the methods embodied in the process of FIG. 35may apply to one or more of the embodiments in which the sensor systemincludes more than one near field only RFID tag or more than one farfield antenna in which coupling and decoupling may selectively occurwith one or more other components at the same or different points intime, such as those embodiments described in connection with FIGS.28-34.

The above-described processes are readily enabled using any of a widevariety of available and/or readily configured control platforms,including partially or wholly programmable platforms as are known in theart or dedicated purpose platforms as may be desired for someapplications. Referring now to FIG. 36, shown is a functional blockdiagram of components of an RFID reader and controller in accordancewith some embodiments. Illustrated is the reader antenna 1806 coupled tothe RFID reader 1808 which is coupled to the controller 1810 (or controlcircuit 1810 or microcontroller 1810). The controller 1810 includes atleast one processor 3602 and at least one memory 3604. The controller1810 is also coupled to a user interface 3606 and/or an externalinterface 3608.

The controller 1810 can comprise a fixed-purpose controller or apartially or wholly programmable controller including the processor 3602and at least one memory 3604. In some embodiments, the memory 3604stores executable program code or instructions that when executed by theprocessor 3602 cause the controller 1810 to carry out one or more of thesteps, actions, or functionality as described herein. Additionally, thememory 3604 can serve to store working data and set up or sensorconfiguration parameters, e.g., parameters that define the ID of nearfield only RFID tags that will be used as sensors, parameters thatdefine the type of sensor with state/event correlation information,parameters defining subsequent notifications and/or actions to be takenresponsive to certain states/events, etc.

So configured, for example, this controller 1810 can cause the RFID tagreader 1808 (or readers) to transmit interrogation signals via theantenna 1806 and to receive and process reflected signals received atthe antenna 1806. Furthermore, the controller can be configured throughexecution of program code by the processor to perform variouscorrelations described herein, such as the determination of state/s ofthe RFID device, the occurrence of event/s based on the reading or notreading of the RFID device, the determination of the transition of theRFID device between coupled and decoupled positioning of the near fieldonly RFID tag and the far field antenna.

In some embodiments, the user interface 3606 provides an interface toload or program data or parameters regarding RFID tag IDs or data thatwill be assigned as RFID sensors. In this way, the memory of thecontroller 1810 is programmed with settings and data so that thecontroller can interpret read or not read RFID devices to correlatestates and/or events. In some case, a detected event will trigger theoutputting of a command or other signal to the user interface to notifythe user of a condition that may require further action. For example, inthe event the reading of a given tag by a reader having an antenna inthe far field is correlated to a condition that a customer has requestedhelp in an area of a retail store, for example, the controller 1810 canoutput an notification to store employees to provide such assistance.Such notifications may be displayed on a display screen or coupled to anetwork (e.g., using the external interface 3608). In some embodiments,the reading of an RFID device in which the near field only RFID tag andthe far field antenna have been located to be read in the far field maytrigger an alarm or otherwise indicate that a door is open that shouldbe closed, for example. Personnel can be alerted to such conditionsthrough signaling output by the controller 1810 and further processed bythe device/s receiving this signaling.

Such an apparatus may be comprised of a plurality of physically distinctelements as is suggested by the illustration shown in FIG. 36. It isalso possible, however, to view this illustration as comprising alogical view, in which case one or more of these elements can be enabledand realized via a shared platform.

In some embodiments, RFID based sensors can leverage readerinfrastructure set up in applications in implementing carton level anditem level tagging, and provide inexpensive, indirectly-powered andflexible RFID devices that can be easily located in a region. The use ofRFID sensors of some embodiments will allow unique sensing opportunitieswithin a carton level or item level tagging application. The use of suchsensor systems may lead to improved efficiencies in a retail environmentallowing for better control of inventory and items in a salesfloor,possibly leading to overall retailer savings, such saving possiblypassed to consumers in improved availability of products and lowerconsumer prices.

Furthermore, the described features, structures, or characteristics ofthe invention may be combined in any suitable manner in one or moreembodiments. In the following description, numerous specific details areprovided to provide a thorough understanding of embodiments of theinvention. One skilled in the relevant art will recognize, however, thatthe invention can be practiced without one or more of the specificdetails, or with other methods, components, materials, and so forth. Inother instances, well-known structures, materials, or operations are notshown or described in detail to avoid obscuring aspects of theinvention.

While the invention herein disclosed has been described by means ofspecific embodiments, examples and applications thereof, numerousmodifications and variations could be made thereto by those skilled inthe art without departing from the scope of the invention set forth inthe claims.

1. A radio frequency identification (RFID) sensor system comprising: anRFID device comprising: a near field only RFID tag, wherein the nearfield only RFID tag in and of itself does not function as a far fieldRFID tag; a conductive element independent from the near field only RFIDtag and configured to function as a far field antenna; and a couplingstructure coupled to the near field only RFID tag and the conductiveelement, wherein the coupling structure is configured to selectivelylocate the near field only RFID tag and the conductive element in atleast a first position and a second position relative to each other;wherein the first position locates the near field only RFID tag and theconductive element relative to each other such that the conductiveelement is sufficiently decoupled from the near field only RFID tag inorder that the RFID device only operates in a near field with respect toan RFID reader; and wherein the second position locates the near fieldonly RFID tag and the conductive element relative to each other suchthat the conductive element is sufficiently coupled to the near fieldonly RFID tag such that the RFID device operates in both the near fieldand a far field with respect to the RFID reader.
 2. The system of claim1 further comprising: the RFID reader located within the far field andoutside of the near field with respect to the RFID device, the RFIDreader configured to read the RFID device only when the couplingstructure locates the near field only RFID tag and the conductiveelement in the second position when the RFID device operates in both thenear field and the far field; and a controller coupled to the RFIDreader and configured to receive signaling from the RFID reader andcorrelate a reading of the RFID device to a first state of the RFIDdevice.
 3. The system of claim 2 wherein the controller is configured tocorrelate the first state of the RFID device to an occurrence of a firstevent.
 4. The system of claim 2 wherein, when the near field only RFIDtag and the conductive element are in the first position, the controlleris configured to correlate a lack of the signaling received from theRFID reader corresponding to the RFID device to a second state of theRFID device.
 5. The system of claim 4 wherein the controller isconfigured to correlate the second state of the RFID device to anoccurrence of a second event.
 6. The system of claim 2 wherein the nearfield only RFID tag stores data that is communicated to the RFID readerwhen the near field only RFID tag and the conductive element are in thesecond position.
 7. The system of claim 6 wherein the controller isconfigured to process at least a portion of the data from the RFIDdevice and correlate the at least a portion of the data to the firststate of the RFID device.
 8. The system of claim 1 further comprising:the RFID reader located in the near field with respect to the RFIDdevice, the RFID reader and configured to read the RFID device when thecoupling structure locates the near field only RFID tag and theconductive element in at least one or both of the first position and thesecond position; and a controller coupled to the RFID reader andconfigured to receive signaling from the RFID reader.
 9. The system ofclaim 1 wherein the RFID reader is located within the far field andoutside of the near field with respect to the RFID device, wherein thecontroller is configured to sense an occurrence of a transition ofbetween the first position and the second position.
 10. The system ofclaim 9 wherein the controller is configured to correlate to theoccurrence of the transition to an occurrence of an event.
 11. Thesystem of claim 1 wherein the coupling structure comprises: a firstportion coupled to the near field only RFID tag; and a second portioncoupled to the conductive element, wherein one or both of the firstportion and the second portion are configured to be physically movableto locate the near field only RFID tag and the conductive elementbetween at least the first position and the second position.
 12. Thesystem of claim 11 wherein one of the first portion and the secondportion is stationary and another of the first portion and the secondportion is configured to be movable to locate the near field only RFIDtag and the conductive element in at least the first position and thesecond position relative to each other.
 13. The system of claim 11wherein the first portion and the second portion are each configured tobe movable relative to each other to locate the near field only RFID tagand the conductive element in at least the first position and the secondposition relative to each other.
 14. The system of claim 11 wherein thefirst portion and the second portion are separate physical structures.15. The system of claim 11 wherein the first portion and the secondportion are integrated into a single structure.
 16. The system of claim1 wherein the first position may be at one or more of a plurality oflocations.
 17. The system of claim 1 wherein the near field and the farfield are defined as a function of interrogation signals from the RFIDreader having a frequency selected from one of the following frequencybands: a low frequency (LF) band of about 125-134 kHz, a high frequency(HF) band including 13.56 MHz, an ultra high frequency (UHF) band ofabout at 860-960 MHz, and a microwave frequency band of about 2.4 and5.8 GHz.
 18. The system of claim 1 wherein the coupling structure isconfigured to magnetically or capacitively couple the conductive elementto the near field only RFID tag when in the second position.
 19. Thesystem of claim 1 wherein the coupling structure is configured toelectrically couple the conductive element to the near field only RFIDtag when in the second position.
 20. The system of claim 1 wherein thenear field is defined as a first region about the RFID device within onefull wavelength of a carrier wave of interrogation signals from the RFIDreader and the far field is defined as a second region about the RFIDdevice beyond one full wavelength of the carrier wave.
 21. A method forusing a radio frequency identification (RFID) device as a sensorcomprising: locating a near field only RFID tag and a conductive elementof an RFID device at one of a first position and a second positionrelative to each other, wherein the near field only RFID tag in and ofitself does not function as a far field RFID tag, wherein the conductiveelement is configured to function as a far field antenna, wherein thefirst position locates the near field only RFID tag and the conductiveelement relative to each other such that the conductive element issufficiently decoupled from the near field only RFID tag in order thatthe RFID device only operates in a near field with respect to an RFIDreader, wherein the second position locates the near field only RFID tagand the conductive element relative to each other such that theconductive element is sufficiently coupled to the near field only RFIDtag such that the RFID device operates in both the near field and thefar field with respect to the RFID reader; and locating the near fieldonly RFID tag and the conductive element at another of the firstposition and the second position relative to each other.
 22. The methodof claim 21 further comprising: reading, in response to the locating thenear field only RFID tag and the conductive element at the secondposition, the RFID device using the RFID reader located in the far fieldand outside of the near field with respect to the RFID device, whereinthe RFID reader can not read the RFID device when the near field onlyRFID tag and the conductive element are in the first position.
 23. Themethod of claim 22 further comprising: correlating the reading of theRFID device as a first state of the RFID device.
 24. The method of claim22 further comprising: determining an occurrence of a first event basedon the first state.
 25. The method of claim 22 further comprising:Correlating, in response to the locating the near field only RFID tagand the conductive element at the first position, a lack of reading ofthe RFID device as a second state of the RFID device.
 26. The method ofclaim 25 further comprising: determining an occurrence of a second eventbased on the second state.
 27. The method of claim 22 furthercomprising: reading, in response to the locating the near field onlyRFID tag and the conductive element at one or both of the first positionand the second position, the RFID device using the RFID reader locatedin the near field with respect to the RFID device,
 28. The method ofclaim 21 further comprising sensing an occurrence of the second locatingstep using the RFID reader located in the far field and outside of thenear field with respect to the RFID device.
 29. The system of claim 28further comprising correlating the occurrence of the second locatingstep to an occurrence of an event.
 30. The method of claim 21 whereinthe locating the near field only RFID tag and the conductive element atthe other of the first position and the second position step comprises:physically moving one or both of the near field only RFID tag and theconductive element relative to each other to the other of the firstposition and the second position.
 31. The method of claim 21 wherein thelocating the near field only RFID tag and the conductive element at theother of the first position and the second position step comprises:physically moving one of the near field only RFID tag and the conductiveelement while the other of the near field only RFID tag and theconductive element is stationary to the other of the first position andthe second position.
 32. The method of claim 21 wherein the near fieldand the far field are defined as a function of interrogation signalsfrom the RFID reader having a frequency selected from one of thefollowing frequency bands: a low frequency (LF) band of about 125-134kHz, a high frequency (HF) band including 13.56 MHz, an ultra highfrequency (UHF) band of about at 860-960 MHz, and a microwave frequencyband of about 2.4 and 5.8 GHz.
 33. The method of claim 21 wherein whenin the second position, the conductive element is magnetically orcapacitively coupled to the near field only RFID tag such that the RFIDdevice operates in both the near field and the far field with respect tothe RFID reader.
 34. The method of claim 21 wherein when in the firstposition, the conductive element is electrically coupled to the nearfield only RFID tag such that the RFID device operates in both the nearfield and the far field with respect to the RFID reader.